Resist composition, method of forming resist pattern, polymeric compound and compound

ABSTRACT

There is provided a resist composition which generates acid upon exposure and exhibits changed solubility in a developing solution by the action of acid, including a base component (A) which exhibits changed solubility in a developing solution by the action of acid, wherein the base component (A) contains a polymeric compound (A1) having a structural unit (a0) represented by general formula (a0) shown below. In the formula, A″ represents an oxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atoms which may contain an oxygen atom or a sulfur atom; R 1  represents a lactone-containing cyclic group, an —SO 2 — containing cyclic group or a carbonate-containing cyclic group; and W 2  represents a group which is formed by polymerization reaction of a group containing a polymerizable group.

TECHNICAL FIELD

The present invention relates to a resist composition, a method offorming a resist pattern using the same, a polymeric compound useful forthe resist composition, and a compound useful as a raw material for thepolymeric compound.

Priority is claimed on Japanese Patent Application No. 2012-112722,filed May 16, 2012, and Japanese Patent Application No. 2012-258947,filed Nov. 27, 2012, the contents of which are incorporated herein byreference.

BACKGROUND ART

In lithography techniques, for example, a resist film composed of aresist material is formed on a substrate, and the resist film issubjected to selective exposure, followed by development, therebyforming a resist pattern having a predetermined shape on the resistfilm. A resist material in which the exposed portions of the resist filmbecome soluble in a developing solution is called a positive-type, and aresist material in which the exposed portions of the resist film becomeinsoluble in a developing solution is called a negative-type.

In recent years, in the production of semiconductor elements and liquidcrystal display elements, advances in lithography techniques have leadto rapid progress in the field of pattern miniaturization. Typically,these miniaturization techniques involve shortening the wavelength(increasing the energy) of the exposure light source. Conventionally,ultraviolet radiation typified by g-line and i-line radiation has beenused, but nowadays KrF excimer lasers and ArF excimer lasers arestarting to be introduced in mass production. Furthermore, research isalso being conducted into lithography techniques that use an exposurelight source having a wavelength shorter (energy higher) than theseexcimer lasers, such as electron beam (EB), extreme ultravioletradiation (EUV), and X ray.

Resist materials for use with these types of exposure light sourcesrequire lithography properties such as a high resolution capable ofreproducing patterns of minute dimensions, and a high level ofsensitivity to these types of exposure light sources.

As a resist material that satisfies these conditions, a chemicallyamplified composition is used, which includes a base material componentthat exhibits a changed solubility in a developing solution under theaction of acid and an acid generator component that generates acid uponexposure. For example, in the case where the developing solution is analkali developing solution (alkali developing process), a chemicallyamplified positive resist which contains, as a base component (baseresin), a resin which exhibits increased solubility in an alkalideveloping solution under action of acid, and an acid generator istypically used. If the resist film formed using the resist compositionis selectively exposed during formation of a resist pattern, then withinthe exposed portions, acid is generated from the acid generatorcomponent, and the action of this acid causes an increase in thepolarity of the base resin, making the exposed portions soluble in thealkali developing solution. Thus, by conducting alkali developing, theunexposed portions remain to form a positive resist pattern. On theother hand, when such a base resin is applied to a solvent developingprocess using a developing solution containing an organic solvent(organic developing solution), the solubility of the exposed portions inan organic developing solution is decreased. As a result, the unexposedportions of the resist film are dissolved and removed by the organicdeveloping solution, and a negative resist pattern in which the exposedportions are remaining is formed. Such a solvent developing process forforming a negative-tone resist composition is sometimes referred to as“negative-tone developing process” (for example, see Patent Document 1).

In general, the base resin for a chemically amplified resist compositioncontains a plurality of structural units for improving lithographyproperties and the like. For example, in the case of a resin compositionwhich exhibits increased solubility in an alkali developing solution bythe action of acid, a structural unit containing an acid decomposablegroup which is decomposed by the action of acid generated from an acidgenerator component and exhibits increased polarity. Further, astructural unit containing a lactone-containing cyclic group or astructural unit containing a polar group such as a hydroxy group is used(for example, see Patent Document 2).

Recently, as progress is made in development of new lithographytechniques such as immersion exposure, various studies on a base resinhave been conducted. For example, in Patent Documents 3 and 4, apolymeric compound containing a monomer unit having a lactone skeletonrepresented by a specific general formula is disclosed, which is usedfor a chemically amplified resist composition, in particular, for apolymeric compound used in immersion exposure.

DOCUMENTS OF RELATED ART Patent Document

-   [Patent Document 1] Japanese Unexamined Patent Application, First    Publication No. 2009-025723-   [Patent Document 2] Japanese Unexamined Patent Application, First    Publication No. 2003-241385-   [Patent Document 3] Japanese Unexamined Patent Application, First    Publication No. 2010-150447-   [Patent Document 4] Japanese Unexamined Patent Application, First    Publication No. 2010-150448

SUMMARY OF THE INVENTION

As further progress is made in lithography techniques andminiaturization of resist patterns, further improvement in resistmaterials has been demanded in terms of various lithography properties.

For example, improvement in exposure latitude (EL), line width roughness(LWR) and mask reproducibility are also required, as well as improvementin sensitivity and resolution.

Further, in the case where a resist pattern is formed by using achemically amplified resist composition including a polymeric compoundwhich contains a structural unit having a lactone-containing cyclicgroup as a base resin, decrease in film thickness during post exposurebake is likely to be caused. Particularly, the decrease in filmthickness is likely to be caused at exposed portions. Further, in theaforementioned negative-tone developing process, there is a problem inthat the film thickness at exposed portions remaining as a resistpattern is decreased during conducting development using an organicdeveloping solution. The decrease (film shrinkage) in film thicknessafter post exposure bake or after development causes the defects ofetching during etching a substrate while using a resist pattern formedas a mask. Therefore, improvement of film thickness has been demanded.

The present invention takes the above circumstances into consideration,with an object of providing a resist composition exhibiting excellentlithography properties, a method of forming a resist pattern using theresist composition, a polymer compound useful for the resistcomposition, and a compound useful as a raw material for the polymericcompound.

A first aspect of the present invention for solving the aforementionedproblems is a resist composition which generates acid upon exposure andexhibits changed solubility in a developing solution under action ofacid,

including a base component (A) which exhibits changed solubility in adeveloping solution under action of acid, wherein

the base component (A) contains a polymer compound (A1) having astructural unit (a0) represented by general formula (a0) shown below.

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; R¹ represents a lactone-containing cyclic group, an—SO₂— containing cyclic group or a carbonate-containing cyclic group;and W² represents a group which is formed by polymerization reaction ofa group containing a polymerizable group.

A second aspect of the present invention is a method of forming a resistpattern, including forming a resist film on a substrate using a resistcomposition according to the first aspect, subjecting the resist film toexposure, and subjecting the resist film to developing to form a resistpattern.

A third aspect of the present invention is a polymeric compound having astructural unit (a0) represented by general formula (a0) shown below.

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; R¹ represents a lactone-containing cyclic group, an—SO₂— containing cyclic group or a carbonate-containing cyclic group;and W² represents a group which is formed by polymerization reaction ofa group containing a polymerizable group.

A fourth aspect of the present invention is a compound represented bygeneral formula (I) shown below.

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; R¹ represents a lactone-containing cyclic group, an—SO₂— containing cyclic group or a carbonate-containing cyclic group;and R² represents a group containing a polymerizable group.

A fifth aspect of the present invention is a compound represented bygeneral formula (II) shown below.

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; and R′ represents a lactone-containing cyclic group,an —SO₂— containing cyclic group or a carbonate-containing cyclic group.

According to the present invention, there are provided a resistcomposition exhibiting excellent lithography properties, a method offorming a resist pattern using the resist composition, a polymercompound useful for the resist composition, and a compound useful as araw material for the polymeric compound.

MODE FOR CARRYING OUT THE INVENTION

In the present description and claims, the term “aliphatic” is arelative concept used in relation to the term “aromatic”, and defines agroup or compound that has no aromaticity.

The term “alkyl group” includes linear, branched or cyclic, monovalentsaturated hydrocarbon, unless otherwise specified.

The term “alkylene group” includes linear, branched or cyclic, divalentsaturated hydrocarbon, unless otherwise specified. The same applies forthe alkyl group within an alkoxy group.

A “halogenated alkyl group” is a group in which part or all of thehydrogen atoms of an alkyl group is substituted with a halogen atom.Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

A “fluorinated alkyl group” or a “fluorinated alkylene group” is a groupin which part or all of the hydrogen atoms of an alkyl group or analkylene group have been substituted with fluorine atom(s).

The term “structural unit” refers to a monomer unit that contributes tothe formation of a polymeric compound (resin, polymer, copolymer).

A “structural unit derived from an acrylate ester” refers to astructural unit that is formed by the cleavage of the ethylenic doublebond of an acrylate ester.

An “acrylate ester” refers to a compound in which the terminal hydrogenatom of the carboxy group of acrylic acid (CH₂═CH—COOH) has beensubstituted with an organic group.

The acrylate ester may have the hydrogen atom bonded to the carbon atomon the α-position substituted with a substituent. The substituent(R^(α)) that substitutes the hydrogen atom bonded to the carbon atom onthe α-position is an atom other than hydrogen or a group, and examplesthereof include an alkyl group of 1 to 5 carbon atoms and a halogenatedalkyl group of 1 to 5 carbon atoms. Further, an acrylate ester havingthe hydrogen atom bonded to the carbon atom on the α-positionsubstituted with a substituent (R^(α)) in which the substituent has beensubstituted with a substituent containing an ester bond (e.g., anitaconic acid diester), or an acrylic acid having the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent (R^(a)) in which the substituent has been substituted with ahydroxyalkyl group or a group in which the hydroxy group within ahydroxyalkyl group has been modified (e.g., α-hydroxyalkyl acrylateester) can be mentioned as an acrylate ester having the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent. A carbon atom on the α-position of an acrylate ester refersto the carbon atom bonded to the carbonyl group, unless specifiedotherwise.

Hereafter, an acrylate ester having the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent issometimes referred to as “α-substituted acrylate ester”. Further,acrylate esters and α-substituted acrylate esters are collectivelyreferred to as “(α-substituted) acrylate ester”.

A “structural unit derived from acrylaminde” refers to a structural unitthat is formed by the cleavage of the ethylenic double bond ofacrylaminde.

The acrylamide may have the hydrogen atom bonded to the carbon atom onthe α-position substituted with a substituent, and may have either orboth terminal hydrogen atoms on the amino group of acrylamidesubstituted with a substituent. A carbon atom on the α-position of anacrylamide refers to the carbon atom bonded to the carbonyl group,unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof acrylamide, the same substituents as those described above for thesubstituent (R^(α)) on the α-position of the aforementionedα-substituted acrylate ester can be mentioned.

A “structural unit derived from hydroxystyrene or a hydroxystyrenederivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of hydroxystyrene or a hydroxystyrenederivative.

The term “hydroxystyrene derivative” includes compounds in which thehydrogen atom at the α-position of hydroxystyrene has been substitutedwith another substituent such as an alkyl group or a halogenated alkylgroup; and derivatives thereof. Examples of the derivatives thereofinclude hydroxystyrene in which the hydrogen atom of the hydroxy grouphas been substituted with an organic group and may have the hydrogenatom on the α-position substituted with a substituent; andhydroxystyrene which has a substituent other than a hydroxy group bondedto the benzene ring and may have the hydrogen atom on the α-positionsubstituted with a substituent. Here, the α-position (carbon atom on theα-position) refers to the carbon atom having the benzene ring bondedthereto, unless specified otherwise.

As the substituent which substitutes the hydrogen atom on the α-positionof hydroxystyrene, the same substituents as those described above forthe substituent on the α-position of the aforementioned α-substitutedacrylate ester can be mentioned.

A “structural unit derived from vinylbenzoic acid or a vinylbenzoic acidderivative” refers to a structural unit that is formed by the cleavageof the ethylenic double bond of vinylbenzoic acid or a vinylbenzoic acidderivative.

The term “vinylbenzoic acid derivative” includes compounds in which thehydrogen atom at the α-position of vinylbenzoic acid has beensubstituted with another substituent such as an alkyl group or ahalogenated alkyl group; and derivatives thereof. Examples of thederivatives thereof include benzoic acid in which the hydrogen atom ofthe carboxy group has been substituted with an organic group and mayhave the hydrogen atom on the α-position substituted with a substituent;and benzoic acid which has a substituent other than a hydroxy group anda carboxy group bonded to the benzene ring and may have the hydrogenatom on the α-position substituted with a substituent. Here, theα-position (carbon atom on the α-position) refers to the carbon atomhaving the benzene ring bonded thereto, unless specified otherwise.

The term “styrene” includes styrene itself and compounds in which thehydrogen atom at the α-position of styrene has been substituted withanother substituent such as an alkyl group or a halogenated alkyl group.

A “structural unit derived from styrene or a styrene derivative” refersto a structural unit that is formed by the cleavage of the ethylenicdouble bond of styrene or a styrene derivative.

As the alkyl group as a substituent on the α-position, a linear orbranched alkyl group is preferable, and specific examples include alkylgroups of 1 to 5 carbon atoms, such as a methyl group, an ethyl group, apropyl group, an isopropyl group, an n-butyl group, an isobutyl group, atert-butyl group, a pentyl group, an isopentyl group and a neopentylgroup.

Specific examples of the halogenated alkyl group as the substituent onthe α-position include groups in which part or all of the hydrogen atomsof the aforementioned “alkyl group as the substituent on the α-position”are substituted with halogen atoms. Examples of the halogen atom includea fluorine atom, a chlorine atom, a bromine atom and an iodine atom, anda fluorine atom is particularly desirable.

Specific examples of the hydroxyalkyl group as the substituent on theα-position include groups in which part or all of the hydrogen atoms ofthe aforementioned “alkyl group as the substituent on the α-position”are substituted with a hydroxy group. The number of hydroxy groupswithin the hydroxyalkyl group is preferably 1 to 5, and most preferably1.

The expression “may have a substituent” means that a case where ahydrogen atom (—H) is substituted with a monovalent group, or a casewhere a methylene (—CH₂—) group is substituted with a divalent group.

The term “exposure” is used as a general concept that includesirradiation with any form of radiation.

An “organic group” refers to a group containing a carbon atom, and mayinclude atoms other than carbon atoms (e.g., a hydrogen atom, an oxygenatom, a nitrogen atom, a sulfur atom, a halogen atom (such as a fluorineatom and a chlorine atom) and the like).

<<Resist Composition>>

The resist composition according to a first aspect of the presentinvention is a resist composition which generates acid upon exposure andexhibits changed solubility in a developing solution under action ofacid, and which includes a base component (A) which exhibits changedsolubility in a developing solution under action of acid (hereafter,referred to as “component (A)”).

When a resist film is formed using the resist composition and the formedresist film is subjected to a selective exposure, acid is generated atexposed portions, and the generated acid acts on the component (A) tochange the solubility of the component (A) in a developing solution,whereas the solubility of the component (A) in a developing solution isnot changed at unexposed portions, thereby generating difference insolubility in a developing solution between exposed portions andunexposed portions. Therefore, by subjecting the resist film todevelopment, the exposed portions are dissolved and removed to form apositive-tone resist pattern in the case of a positive resist, whereasthe unexposed portions are dissolved and removed to form a negative-toneresist pattern in the case of a negative resist.

In the present specification, a resist composition which forms apositive resist pattern by dissolving and removing the exposed portionsis called a positive resist composition, and a resist composition whichforms a negative resist pattern by dissolving and removing the unexposedportions is called a negative resist composition.

The resist composition of the present invention may be either a positiveresist composition or a negative resist composition.

Further, in the formation of a resist pattern, the resist composition ofthe present invention can be applied to an alkali developing processusing an alkali developing solution in the developing treatment, or asolvent developing process using a developing solution containing anorganic solvent (organic developing solution) in the developingtreatment.

The resist composition of the present invention has a function ofgenerating acid upon exposure, and in the resist composition, thecomponent (A) may generate acid upon exposure, or an additive componentother than the component (A) may generate acid upon exposure.

More specifically, the resist composition of the present invention maybe

a resist composition (1) containing an acid generator component (B)which generates acid upon exposure (hereafter, referred to as “component(B)”;

a resist composition (2) in which the component (A) is a component whichgenerates acid upon exposure; or

a resist composition (3) in which the component (A) is a component whichgenerates acid upon exposure, and further containing an acid generatorcomponent (B).

That is, when the resist composition of the present invention is theaforementioned resist composition (2) or (3), the component (A) is a“base component which generates acid upon exposure and exhibits changedsolubility in a developing solution under action of acid”. In the casewhere the component (A) is a base component which generates acid uponexposure and exhibits changed solubility in a developing solution underaction of acid, the component (A1) described later is preferably apolymeric compound which generates acid upon exposure and exhibitschanged solubility in a developing solution under action of acid. As thepolymeric compound, a resin having a structural unit which generatesacid upon exposure can be used. As the structural unit which generatesacid upon exposure, a conventional structural unit can be used.

The resist composition of the present invention is particularlypreferably the aforementioned resist composition (1).

<Component (A)>

In the present invention, the term “base component” refers to an organiccompound capable of forming a film, and is preferably an organiccompound having a molecular weight of 500 or more. When the organiccompound has a molecular weight of 500 or more, the film-forming abilityis improved, and a resist pattern of nano level can be easily formed.

The organic compound used as the base component is broadly classifiedinto non-polymers and polymers.

In general, as a non-polymer, any of those which have a molecular weightin the range of 500 to less than 4,000 is used. Hereafter, a “lowmolecular weight compound” refers to a non-polymer having a molecularweight in the range of 500 to less than 4,000.

As a polymer, any of those which have a molecular weight of 1,000 ormore is generally used. Hereafter, a “resin” refers to a polymer havinga molecular weight of 1,000 or more.

As the molecular weight of the polymer, the weight average molecularweight in terms of the polystyrene equivalent value determined by gelpermeation chromatography (GPC) is used.

As the component (A), a resin, a low molecular weight compound, or acombination thereof may be used.

The component (A) may be a resin that exhibits increased solubility in adeveloping solution under action of acid or a resin that exhibitsdecreased solubility in a developing solution under action of acid.

In the present invention, the component (A) may be a component thatgenerates acid upon exposure.

When the resist composition of the present invention is a “negativeresist composition for alkali developing process” that forms anegative-tone resist pattern in an alkali developing process (or a“positive resist composition for solvent developing process” that formsa positive-tone resist pattern in a solvent developing process), as thecomponent (A), a base component (A-2) that is soluble in an alkalideveloping solution (hereafter, this base component is sometimesreferred to as “component (A-2)”) is preferably used, and across-linking component is further added. In such a resist composition,when acid is generated upon exposure, the action of the acid causescross-linking between the component (A-2) and the cross-linkingcomponent. As a result, the solubility of the resist composition in analkali developing solution is decreased (the solubility of the resistcomposition in an organic developing solution is increased). Therefore,in the formation of a resist pattern, by conducting selective exposureof a resist film formed by applying the resist composition to asubstrate, the exposed portions become insoluble in an alkali developingsolution (soluble in an organic developing solution), whereas theunexposed portions remain soluble in an alkali developing solution(insoluble in an organic developing solution), and hence, a negativeresist pattern can be formed by conducting development using an alkalideveloping solution. On the other hand, when an organic developingsolution is used as the developing solution, a positive resist patterncan be formed.

As the component (A-2), a resin that is soluble in an alkali developingsolution (hereafter, referred to as “alkali-soluble resin”) is used.

Examples of the alkali soluble resin include a resin having a structuralunit derived from at least one of α-(hydroxyalkyl)acrylic acid and analkyl ester of α-(hydroxyalkyl)acrylic acid (preferably an alkyl esterhaving 1 to 5 carbon atoms), as disclosed in Japanese Unexamined PatentApplication, First Publication No. 2000-206694; an acrylic resin whichhas a sulfonamide group and may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent orpolycycloolefin resin having a sulfoneamide group, as disclosed in U.S.Pat. No. 6,949,325; an acrylic resin which may have the hydrogen atombonded to the carbon atom on the α-position substituted with asubstituent and having a fluorinated alcohol, as disclosed in U.S. Pat.No. 6,949,325, Japanese Unexamined Patent Application, First PublicationNo. 2005-336452 or Japanese Unexamined Patent Application, FirstPublication No. 2006-317803; and a polycyclolefin resin having afluorinated alcohol, as disclosed in Japanese Unexamined PatentApplication, First Publication No. 2006-259582. These resins arepreferable in that a resist pattern can be formed with minimal swelling.

Here, the term “α-(hydroxyalkyl)acrylic acid” refers to one or both ofacrylic acid in which a hydrogen atom is bonded to the carbon atom onthe α-position having the carboxyl group bonded thereto, andα-hydroxyalkylacrylic acid in which a hydroxyalkyl group (preferably ahydroxyalkyl group of 1 to 5 carbon atoms) is bonded to the carbon atomon the α-position.

As the cross-linking agent, typically, an amino-based cross-linkingagent such as a glycoluril having a methylol group or alkoxymethylgroup, or a melamine-based cross-linking agent is preferable, as itenables formation of a resist pattern with minimal swelling. The amountof the cross-linking agent added is preferably within a range from 1 to50 parts by weight, relative to 100 parts by weight of thealkali-soluble resin.

In the case where the resist composition of the present invention is aresist composition which forms a positive pattern in an alkalideveloping process and a negative pattern in a solvent developingprocess (i.e., a positive type resist compound for alkali developingprocess) or a resist composition which forms a negative pattern in asolvent developing process (i.e., a negative type resist composition forsolvent developing process), as a component (A), it is preferable to usea base component (A-1) (hereafter, referred to as “component (A-1)”)which exhibits increased polarity by the action of acid.

By using the component (A-1), since the polarity of the base componentchanges prior to and after exposure, an excellent development contrastcan be obtained not only in an alkali developing process, but also in asolvent developing process.

More specifically, in the case of applying an alkali developing process,the component (A-1) is substantially insoluble in an alkali developingsolution prior to exposure, but when acid is generated upon exposure,the action of this acid causes an increase in the polarity of the basecomponent, thereby increasing the solubility of the component (A-1) inan alkali developing solution. Therefore, in the formation of a resistpattern, by conducting selective exposure of a resist film formed byapplying the resist composition to a substrate, the exposed portionschange from an insoluble state to a soluble state in an alkalideveloping solution, whereas the unexposed portions remain insoluble inan alkali developing solution, and hence, a positive resist pattern canbe formed by alkali developing.

On the other hand, in the case of a solvent developing process, thecomponent (A-1) exhibits high solubility in an organic developingsolution prior to exposure, and when acid is generated upon exposure,the polarity of the component (A-1) is increased by the action of thegenerated acid, thereby decreasing the solubility of the component (A-1)in an organic developing solution. Therefore, in the formation of aresist pattern, by conducting selective exposure of a resist film formedby applying the resist composition to a substrate, the exposed portionschanges from an soluble state to an insoluble state in an organicdeveloping solution, whereas the unexposed portions remain soluble in anorganic developing solution. As a result, by conducting developmentusing an organic developing solution, a contrast can be made between theexposed portions and unexposed portions, thereby enabling the formationof a negative resist pattern.

In the present invention, the component (A) is preferably a component(A-1).

[Polymeric compound (A1)]

The component (A) includes a polymeric compound (A1) (hereafter,referred to as “component (A1)”) including a structural unit (a0)described later.

As the component (A1), the component (A-1) is preferable.

(Structural Unit (a0))

The structural unit (a0) is a structural unit represented by generalformula (a0) shown below.

The structural unit (a0) has R¹ (wherein R¹ represents alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group) at the terminal thereof, and has astructure represented by “—O-(a specific lactone-containing cyclicgroup)-C(═O)—O—” between W² and R¹. Therefore, the structural unit (a0)has a steric bulkiness and high polarity. As a result, the adhesionbetween the resist film and the substrate, and the compatibility with adeveloping solution containing water, such as an alkali developingsolution is enhanced, and the lithographic properties are improved.Further, the problem of the decrease in film thickness (i.e., filmshrinkage) after post exposure bake (PEB) or after development isimproved, and for example, in a solvent developing process, anegative-tone pattern can be formed with a high residual film ratio.

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; R¹ represents a lactone-containing cyclic group, an—SO₂— containing cyclic group or a carbonate-containing cyclic group;and W² represents a group which is formed by polymerization reaction ofa group containing a polymerizable group.

In general formula (a0), A″ represents an oxygen atom, a sulfur atom, oran alkylene group of 1 to 5 carbon atoms which may contain an oxygenatom (—O—) or a sulfur atom (—S—). As the alkylene group of 1 to 5carbon atoms for A″, a linear or branched alkylene group is preferable,and examples thereof include a methylene group, an ethylene group, ann-propylene group and an isopropylene group. Examples of alkylene groupsthat contain an oxygen atom or a sulfur atom include the aforementionedalkylene groups in which —O— or —S— is bonded to the terminal of thealkylene group or present between the carbon atoms of the alkyl group.Specific examples of such alkylene groups include —O—CH₂—, —CH₂—O—CH₂—,—S—CH₂— and —CH₂—S—CH₂—. As A″, an alkylene group of 1 to 5 carbon atomsor —O— is preferable, more preferably an alkylene group of 1 to 5 carbonatoms, and most preferably a methylene group.

In the formula (a0), R¹ represents a lactone-containing cyclic group, an—SO₂-containing cyclic group or a carbonate-containing cyclic group.

The term “lactone-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)— structure (lactone ring). Theterm “lactone ring” refers to a single ring containing a —O—C(═O)—structure, and this ring is counted as the first ring. Alactone-containing cyclic group in which the only ring structure is thelactone ring is referred to as a monocyclic group, and groups containingother ring structures are described as polycyclic groups regardless ofthe structure of the other rings. The lactone-containing cyclic groupmay be either a monocyclic group or a polycyclic group.

The lactone-containing cyclic group for R¹ is not particularly limited,and an arbitrary group may be used. Specific examples include groupsrepresented by general formulas (a2-r-1) to (a2-r-7) shown below. In thepresent specification, “*” in the formula represents a valence bond.

In the formulas, each Ra′²¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; n′ represents aninteger of 0 to 2; and m′ represents 0 or 1.

In general formulas (a2-r-1) to (a2-r-7), A″ is the same as defined forA″ in general formula (a0).

The alkyl group for Ra′²¹ is preferably an alkyl group of 1 to 6 carbonatoms. Further, the alkyl group is preferably a linear alkyl group or abranched alkyl group. Specific examples include a methyl group, an ethylgroup, a propyl group, an isopropyl group, an n-butyl group, an isobutylgroup, a tert-butyl group, a pentyl group, an isopentyl group, aneopentyl group and a hexyl group. Among these, a methyl group or anethyl group is preferable, and a methyl group is particularly desirable.

The alkoxy group for Ra′²¹ is preferably an alkoxy group of 1 to 6carbon atoms.

Further, the alkoxy group is preferably a linear or branched alkoxygroup. Specific examples of the alkoxy groups include the aforementionedalkyl groups for the substituent having an oxygen atom (—O—) bondedthereto.

As examples of the halogen atom for Ra′²¹, a fluorine atom, chlorineatom, bromine atom and iodine atom can be given. Among these, a fluorineatom is preferable.

Examples of the halogenated alkyl group for Ra′²¹ include groups inwhich part or all of the hydrogen atoms within the aforementioned alkylgroups has been substituted with the aforementioned halogen atoms. Asthe halogenated alkyl group, a fluorinated alkyl group is preferable,and a perfluoroalkyl group is particularly desirable.

With respect to —COOR″ and —OC(═O)R″ for Ra′²¹, R″ represents a hydrogenatom or an alkyl group.

The alkyl group for R″ may be linear, branched or cyclic, and preferablyhas 1 to 15 carbon atoms.

When R″ represents a linear or branched alkyl group, it is preferably analkyl group of 1 to 10 carbon atoms, more preferably an alkyl group of 1to 5 carbon atoms, and most preferably a methyl group or an ethyl group.

When R″ is a cyclic alkyl group (cycloalkyl group), it preferably has 3to 15 carbon atoms, more preferably 4 to 12 carbon atoms, and mostpreferably 5 to 10 carbon atoms. As examples of the cycloalkyl group,groups in which one hydrogen atoms have been removed from amonocycloalkane or a polycycloalkane such as a bicycloalkane,tricycloalkane or tetracycloalkane, which may or may not be substitutedwith a fluorine atom or a fluorinated alkyl group, may be used. Specificexamples include groups in which one hydrogen atom has been removed froma monocycloalkane such as cyclopentane and cyclohexane; and groups inwhich one hydrogen atom has been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane.

The hydroxyalkyl group for Ra′²¹ preferably has 1 to 6 carbon atoms, andspecific examples thereof include the aforementioned alkyl groups forthe substituent on α-position in which at least one hydrogen atom hasbeen substituted with a hydroxy group.

Specific examples of the groups represented by the aforementionedgeneral formulas (a2-r-1) to (a2-r-7) are shown below.

An “—SO₂— containing cyclic group” refers to a cyclic group having aring containing —SO₂— within the ring structure thereof, i.e., a cyclicgroup in which the sulfur atom (S) within —SO₂— forms part of the ringskeleton of the cyclic group. The ring containing —SO₂— within the ringskeleton thereof is counted as the first ring. A cyclic group in whichthe only ring structure is the ring that contains —SO₂— in the ringskeleton thereof is referred to as a monocyclic group, and a groupcontaining other ring structures is described as a polycyclic groupregardless of the structure of the other rings. The —SO₂-containingcyclic group may be either a monocyclic group or a polycyclic group.

As the —SO₂— containing cyclic group, a cyclic group containing —O—SO₂—within the ring skeleton thereof, i.e., a cyclic group containing asultone ring in which —O—S-within the —O—SO₂— group forms part of thering skeleton thereof is particularly desirable.

More specific examples of the —SO₂— containing cyclic group includegroups represented by general formulas (a5-r-1) to (a5-r-4) shown below.

In the formulas, each Ra′⁵¹ independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; and n′ represents aninteger of 0 to 2.

In general formulas (a5-r-1) to (a5-r-4), A″ is the same as defined forA″ in general formula (a0).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′⁵¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulas (a5-r-1) to (a5-r-4) are shown below. In the formulasshown below, “Ac” represents an acetyl group.

The term “carbonate-containing cyclic group” refers to a cyclic groupincluding a ring containing a —O—C(═O)—O— structure (carbonate ring).The term “carbonate ring” refers to a single ring containing a—O—C(═O)—O— structure, and this ring is counted as the first ring. Acarbonate-containing cyclic group in which the only ring structure isthe carbonate ring is referred to as a monocyclic group, and groupscontaining other ring structures are described as polycyclic groupsregardless of the structure of the other rings. The carbonate-containingcyclic group may be either a monocyclic group or a polycyclic group.

The carbonate-containing cyclic group for R¹ is not particularlylimited, and an arbitrary group may be used. Specific examples includegroups represented by general formulas (ax3-r-1) to (ax3-r-3) shownbelow.

In the formulas, each Ra′^(x31) independently represents a hydrogenatom, an alkyl group, an alkoxy group, a halogen atom, a halogenatedalkyl group, a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group ora cyano group; R″ represents a hydrogen atom or an alkyl group; A″represents an oxygen atom, a sulfur atom or an alkylene group of 1 to 5carbon atoms which may contain an oxygen atom or a sulfur atom; p′represents an integer of 0 to 2; and q′ represents 0 or 1.

In general formulas (ax3-r-1) to (ax3-r-3), A″ is the same as definedfor A″ in general formula (a0).

Examples of the alkyl group, alkoxy group, halogen atom, halogenatedalkyl group, —COOR″, —OC(═O)R″ and hydroxyalkyl group for Ra′³¹ includethe same groups as those described above in the explanation of Ra′²¹ inthe general formulas (a2-r-1) to (a2-r-7).

Specific examples of the groups represented by the aforementionedgeneral formulas (ax3-r-1) to (ax3-r-3) are shown below.

Among the examples shown above, as R¹, a lactone-containing cyclic groupor an —SO₂— containing cyclic group is preferable, a group representedby the general formula (a2-r-1), (a2-r-2) or (a5-r-1) is morepreferable, and a group represented by any one of the chemical formulas(r-1c-1-1) to (r-1c-1-7), (r-1c-2-1) to (r-1c-2-13), (r-s1-1-1) and(r-s1-1-18) is still more preferable.

In the formula (a0), W² represents a group which is formed bypolymerization reaction of a group containing a polymerizable group.

A “polymerizable group” refers to a group that renders a compoundcontaining the group polymerizable by a radical polymerization or thelike, for example, a group having a carbon-carbon multiple bond such asan ethylenic double bond.

Examples of the polymerizable group include a vinyl group, an allylgroup, an acryloyl group, a methacryloyl group, a fluorovinyl group, adifluorovinyl group, a trifluorovinyl group, adifluorotrifluoromethylvinyl group, a trifluoroallyl group, aperfluoroallyl group, a trifluoromethylacryloyl group, anonylfluorobutylacryloyl group, a vinyl ether group, afluorine-containing vinyl ether group, an allyl ether group, anfluorine-containing allyl ether group, a styryl group, a vinylnaphthylgroup, a fluorine-containing styryl group, a fluorine-containingvinylnaphthyl group, a norbornyl group, a fluorine-containing norbornylgroup, and a silyl group.

The group for W² containing a polymerizable group may be a groupconstituted of only a polymerizable group, or constituted of apolymerizable group and a group other than a polymerizable group.

As the group containing a polymerizable group, a group represented byR²-L¹- [in the formula, R² represents a hydrocarbon group which containsan ethylenic double bond and which may have a substituent, and L¹represents a divalent linking group containing a hetero atom or a singlebond] is preferably used.

The hydrocarbon group for R² is not particularly limited, as long as itcontains an ethylenic double bond, and may be a chain-like hydrocarbongroup, or a hydrocarbon group containing a ring in the structure thereof

As the chain-like hydrocarbon group for R², a chain-like alkenyl groupis preferable. The chain-like alkenyl group may be linear or branched,and preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and particularlypreferably 2 or 3 carbon atoms.

Examples of linear alkenyl groups include a vinyl group, a propenylgroup (an allyl group) and a butynyl group. Examples of branched alkenylgroups include a 1-methylpropenyl group and a 2-methylpropenyl group. Ofthese, a vinyl group or a propenyl group is preferable.

As examples of the hydrocarbon group for R² containing a ring in thestructure thereof, an unsaturated aliphatic hydrocarbon cyclic groupwhich contains an ethylenic double bond in the ring structure thereof, agroup in which the unsaturated aliphatic hydrocarbon cyclic group isbonded to the terminal of the aforementioned linear or branchedaliphatic hydrocarbon group, and a group in which a chain-like alkenylgroup is bonded to the terminal of the a cyclic hydrocarbon group, canbe given.

As the unsaturated aliphatic hydrocarbon cyclic group which contains anethylenic double bond in the ring structure thereof, for example, agroup in which one hydrogen atom has been removed from a monocyclic orpolycyclic cycloolefine can be mentioned. The cycloolefine preferablyhas 3 to 20 carbon atoms, and more preferably 3 to 12 carbon atoms.Examples of the cycloolefine include cyclopropene, cyclobutene,cyclopentene, cyclohexene, cycloheptene, cyclooctene, norbornene,7-oxanorbornene, tetracyclododecene. Among these examples, norbornene ispreferable.

With respect to the group in which the unsaturated aliphatic hydrocarboncyclic group is bonded to the terminal of the aforementioned linear orbranched aliphatic hydrocarbon group, the linear or branched aliphatichydrocarbon group to which the unsaturated aliphatic hydrocarbon cyclicgroup is to be bonded may be saturated or unsaturated. In general, thelinear or branched aliphatic hydrocarbon group is preferably saturated.

The linear or branched aliphatic hydrocarbon group preferably has 1 to10 carbon atoms, more preferably 1 to 6, still more preferably 1 to 4,and most preferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable, and specific examples include a methylene group [—CH₂—], anethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

As the branched aliphatic hydrocarbon group, a branched alkylene groupis preferable, and specific examples include alkylalkylene groups, e.g.,alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—,—C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylenegroups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—,—CH(CH₂CH₃)CH₂—, and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as—CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groupssuch as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. As the alkyl groupwithin the alkylalkylene group, a linear alkyl group of 1 to 5 carbonatoms is preferable.

With respect to the group in which a chain-like alkenyl group is bondedto the terminal of the a cyclic hydrocarbon group, as the chain-likealkenyl group, the same groups as those described above can bementioned.

The cyclic hydrocarbon group to which the chain-like alkenyl group is tobe bonded may be a cyclic aliphatic hydrocarbon group (aliphatic cyclicgroup) or a cyclic aromatic hydrocarbon group (aromatic cyclic group).

The cyclic aliphatic hydrocarbon group may be either saturated orunsaturated. In general, the cyclic aliphatic hydrocarbon group ispreferably saturated.

The aliphatic cyclic group preferably has 3 to 20 carbon atoms, and morepreferably 3 to 12 carbon atoms.

The aliphatic cyclic group may be either a monocyclic group or apolycyclic group. As the monocyclic aliphatic hydrocarbon group, a groupin which one hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 6 carbon atoms, andspecific examples thereof include cyclopentane and cyclohexane. As thepolycyclic aliphatic cyclic group, a group in which one hydrogen atomshave been removed from a polycycloalkane is preferable, and thepolycyclic group preferably has 7 to 12 carbon atoms. Examples of thepolycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

The aromatic cyclic group is a group in which one hydrogen atom has beenremoved from an aromatic ring.

The aromatic cyclic group preferably has 5 to 30 carbon atoms, morepreferably 5 to 20, still more preferably 6 to 15, and most preferably 6to 10. Here, the number of carbon atoms within a substituent(s) is notincluded in the number of carbon atoms of the aromatic cyclic group.

Examples of the aromatic ring include aromatic hydrocarbon rings, suchas benzene, biphenyl, fluorene, naphthalene, anthracene andphenanthrene; and aromatic hetero rings in which part of the carbonatoms constituting the aforementioned aromatic hydrocarbon rings hasbeen substituted with a hetero atom. Examples of the hetero atom withinthe aromatic hetero rings include an oxygen atom, a sulfur atom and anitrogen atom.

The hydrocarbon group for R² may have a hydrogen atom substituted with asubstituent. Examples of substituents include a halogen atom, a hydroxygroup, a hydroxyalkyl group, an alkoxy group, —V²¹—COOR⁰″, and—V²¹—OC(═O)R⁰″. V²¹ represents a single bond or an alkylene group, andR⁰″ represents a hydrogen atom, a hydrocarbon group which may have asubstituent, or an anion group.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

The hydroxyalkyl group and the alkoxy group as the substituent are thesame groups as defined for those described in the explanation for Ra′²¹.

As the alkylene group for V²¹ within —V²¹—COOR⁰″ and —V²¹—OC(═O)R⁰″ as asubstituent, a linear or branched alkylene group is preferable. Examplesof the linear alkylene group or branched alkylene group include the samegroups as those described above in the explanation of the linear orbranched aliphatic hydrocarbon group. The alkylene group preferably has1 to 5 carbon atoms, more preferably 1 to 3 carbon atoms, and mostpreferably 1 carbon atom.

Examples of the hydrocarbon group for R⁰″ which may have a substituentinclude a cyclic group which may have a substituent, a chain-like alkylgroup which may have a substituent, and a chain-like alkenyl group whichmay have a substituent. These groups are the same groups as thosedescribed later for R¹⁰¹ in general formula (b-1) in the explanation ofthe component (B).

Preferable examples of the hydrocarbon group for R⁰″ which may have asubstituent include: an acid dissociable group represented by generalformulas (a1-r-1) to (a1-r-2) described later;

an alkyl group same as those described above for Ra′²¹;

the groups represented by the general formulas (a2-r-1) to (a2-r-7),(a5-r-1) to (a5-r-4), and (ax3-r-1) to (ax3-r-3).

As an example of the anion group for R⁰″, a group represented by generalformulas (r-an-1) to (r-an-4) shown below can be given.

In the formulas, Va′⁶¹ to Va′⁶⁴ represents a single bond or a divalenthydrocarbon group which may have a substituent; La′⁶¹ and La′⁶² eachindependently represents —SO₂—, —CO— or a single bond; La′⁶³ to La′⁶⁵each independently represents —SO₂—, —CO— or a single bond; Ra′⁶¹, Ra′⁶³and Ra′⁶⁴ each independently represents a hydrocarbon group which mayhave a substituent; and M^(m+) represents an organic cation having avalency of m.

The divalent hydrocarbon group for Va′⁶¹ to Va′⁶⁴ which may have asubstituent is the same groups as those described later for the divalenthydrocarbon group in the explanation of the formula (a2-1). Among these,an alkylene group of 1 to 15 carbon atoms, an arylene group of 1 to 15carbon atoms, or a fluorinated arylene group of 1 to 15 carbon atoms ispreferable.

Examples of the hydrocarbon group for Ra′⁶¹, Ra′⁶³ and Ra′⁶⁴ which mayhave a substituent include the same groups as those described above forR⁰″ which may have a substituent.

Examples of the group for R² include a vinyl group, an allyl group, afluorovinyl group, a difluorovinyl group, a trifluorovinyl group, adifluorotrifluoromethylvinyl group, a trifluoroallyl group, aperfluoroallyl group, a styryl group, a vinylnaphthyl group, afluorine-containing styryl group, a fluorine-containing vinylnaphthylgroup, a norbornyl group, a fluorine-containing norbornyl group, and avinyl group or allyl group substituted with a hydroxy group,hydroxyalkyl group, alkoxy group, —V²¹—COOR⁰″ or —V²¹—OC(═O)R⁰″.

With respect to a “divalent linking group containing a hetero atom” forL¹, a hetero atom is an atom other than carbon and hydrogen, andexamples thereof include an oxygen atom, a nitrogen atom, a sulfur atomand a halogen atom.

When L¹ is a divalent linking group containing a hetero atom, thelinking group preferably contains at least one atom selected from thegroup consisting of an oxygen atom, a sulfur atom and a nitrogen atom,and examples thereof include —C(═O)—O—V¹—C(═O)—,—C(═O)—O—V²—O—V¹—C(═O)—, —C(═O)—O—V³—C(═O)—O—V¹—C(═O)—,—C(═O)—O—Ar—O—V¹—C(═O)—, —C(═O)—NH—V¹—C(═O)—, —C(═O)—NH—Ar—C(═O)—,—C(═O)—O—V⁴—NH—C(═O)—, —C(═O)—, —S(═O)₂—, —C(═O)—O—V⁵—, —O—V⁵—, and—O—V¹—C(═O)—.

In the formulas, V¹ to V⁵ each independently represents an alkylenegroup, and Ar represents an arylene group. The alkylene group for V¹ toV⁵ may be chain-like or cyclic. The chain-like alkylene group may belinear or branched, and examples thereof include the same linearalkylene groups and branched alkylene groups as those described abovefor the linear or branched aliphatic hydrocarbon group. As the cyclicalkylene group, a group in which one hydrogen atom has been removed fromthe aforementioned aliphatic cyclic group can be mentioned.

As the alkylene group for V¹, V³ and V⁵, a linear or branched alkylenegroup is preferable, and a methylene group, an ethylene group or analkylmethylene group is more preferable. The alkyl group within thealkylmethylene group is preferably a linear alkyl group of 1 to 5 carbonatoms, more preferably a linear alkyl group of 1 to 3 carbon atoms, andmost preferably a methyl group.

As the alkylene group for V² and V⁴, a linear or branched alkylene groupis preferable, more preferably a linear alkylene group, still morepreferably a linear alkylene group of 1 to 5 carbon atoms, and mostpreferably an ethylene group.

As the arylene group for Ar, a group in which one hydrogen atom has beenremoved from the aforementioned aromatic cyclic group can be mentioned.As the arylene group, a phenylene group or a naphthylene group isparticularly desirable.

Among these examples, as the divalent linking group containing a heteroatom for L¹, a group in which the terminal structure at the side of theoxygen atom adjacent to W² (i.e., oxygen atom (—O—) bonded to R¹) has—C(═O)— or an alkylene group (e.g., V′) is preferable, and a group inwhich the terminal structure at the side of the oxygen atom adjacent toW² has —C(═O)— is more preferable in terms of ease in synthesis.

As the group for W² containing a polymerizable group, a grouprepresented by CH₂═C(R)—V¹⁰-L¹- [in the formula, R represents a hydrogenatom, an alkyl group of 1 to 5 carbon atoms, a halogenated alkyl groupof 1 to 5 carbon atoms, a hydroxyalkyl group, an alkoxy group,—V²¹—COOR⁰″ or —V²¹—OC(═O)R⁰″, wherein V¹⁰ represents an arylene group,an alkylene group or a single bond, and L¹ represents a divalent linkinggroup containing a hetero atom or a single bond] is particularlypreferable.

In the formula, A″, R¹ and L¹ are the same as defined above,

R represents a hydrogen atom, an alkyl group of 1 to 5 carbon atoms, ahalogenated alkyl group of 1 to 5 carbon atoms, a hydroxyalkyl group, analkoxy group, —V²¹—COOR⁰″ or —V²¹—OC(═O)R⁰″.

As the alkyl group of 1 to 5 carbon atoms for R, a linear or branchedalkyl group is preferable, and specific examples thereof include amethyl group, an ethyl group, a propyl group, an isopropyl group, ann-butyl group, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group and a neopentyl group.

Examples of the halogenated alkyl group of 1 to 5 carbon atoms for Rinclude groups in which part or all of the hydrogen atoms within theaforementioned alkyl groups of 1 to 5 carbon atoms has been substitutedwith a halogen atom. Examples of the halogen atom include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is particularly desirable.

The hydroxyalkyl group, alkoxy group, —V²¹—COOR⁰″ and —V²¹—OC(═O)R⁰″ forR are the same groups as defined for those described in the explanationfor R².

As R, a hydrogen atom or a methyl group is particularly desirable interms of industrial availability.

As the arylene group for V¹⁰, a group in which one hydrogen atom hasbeen removed from the aforementioned aromatic cyclic group can bementioned. As the arylene group, a phenylene group or a naphthylenegroup is particularly desirable.

The alkylene group for V¹⁰ may be chain-like or cyclic. The chain-likealkylene group may be linear or branched, and examples thereof includethe same linear alkylene groups and branched alkylene groups as thosedescribed above for the linear or branched aliphatic hydrocarbon group.As the cyclic alkylene group, a group in which one hydrogen atom hasbeen removed from the aforementioned aliphatic cyclic group can bementioned.

As the group for Y¹⁰, an arylene group or a single bond is preferable,and a phenylene group, a naphthylene group or a single bond isparticularly preferable.

In the case where the group for W² containing a polymerizable group isCH₂═C(R)—V¹⁰-L¹-, W² represents a structure formed by the cleavage ofthe ethylenic double bond.

That is, in the case where the group containing a polymerizable group isCH₂═C(R)—V¹⁰-L¹-, the structural unit (a0) is a structural unitrepresented by general formula (a0-1) shown below.

In the formula (a0-1), R, V¹⁰, L¹, A″ and R¹ are the same as definedabove.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms, a halogenated alkyl group of 1 to 5 carbon atoms, ahydroxyalkyl group, an alkoxy group, —V²¹—COOR⁰″ or —V²¹—OC(═O)R⁰″; A″represents an oxygen atom, a sulfur atom or an alkylene group of 1 to 5carbon atoms which may contain an oxygen atom or a sulfur atom; R¹represents a lactone-containing cyclic group, an —SO₂— containing cyclicgroup or a carbonate-containing cyclic group; V¹⁰ represents an arylenegroup, an alkylene group or a single bond; L¹ represents a divalentlinking group containing a hetero atom or a single bond; V²¹ representsa single bond or an alkylene group; and R⁰″ represents a hydrogen atom,a hydrocarbon group which may have a substituent or an anion group.

As the structural unit (a0), a structural unit represented by generalformula (a0-11) or (a0-12) shown below is particularly desirable.

In the formulas, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms, a halogenated alkyl group of 1 to 5 carbon atoms, ahydroxyalkyl group, an alkoxy group, —V²¹—COOR⁰″ or —V²¹—OC(═O)R⁰″; A″represents an oxygen atom, a sulfur atom or an alkylene group of 1 to 5carbon atoms which may contain an oxygen atom or a sulfur atom; R¹represents a lactone-containing cyclic group, an —SO₂— containing cyclicgroup or a carbonate-containing cyclic group; L¹¹ represents—C(═O)—O—V¹—C(═O)—, —C(═O)—O—V²—O—V¹—C(═O)—,—C(═O)—O—V³—C(═O)—O—V¹—C(═O)—, —C(═O)—O—Ar—O—V¹—C(═O)—,—C(═O)—NH—V¹—C(═O)—, —C(═O)—NH—Ar—C(═O)—, —C(═O)—O—V⁴—NH—C(═O)—,—C(═O)—, —S(═O)₂— or —C(═O)—O—V⁵—; V¹² represents an arylene group; L¹²represents —C(═O)—NH—V¹—C(═O)—, —C(═O)—, —O—V¹—C(═O)— or —O—V⁵—; V²¹represents a single bond or an alkylene group; R⁰″ represents a hydrogenatom, a hydrocarbon group which may have a substituent or an aniongroup;

V¹ to V⁵ each independently represents an alkylene group; and Arrepresents an arylene group.

In the formulas (a0-11) and (a0-12), R, A″ and R¹ are the same asdefined above. In the L¹¹ group and L¹² group, V¹ to V⁵ are the same asdefined above.

The arylene group for V¹² is the same as defined for the arylene groupfor V¹⁰.

The structural unit (a0) may have an acid decomposable portion in thestructure thereof.

The “acid decomposable portion” refers to a portion containing a bondcapable of being cleaved by the action of acid.

Examples of the acid decomposable portion include a tertiary alkyl esterstructure and an acetal structure.

In the case where W² contains a tertiary carbon atom bonded to the oxygroup (—O—) within a carbonyloxy group, a tertiary alkyl ester structureis formed, and by the action of acid, the bond between the oxygen atomwithin the carbonyloxy group and the tertiary carbon atom bonded to theoxygen atom within the carbonyloxy group is cleaved.

Further, W² contains an (alkyl)methylene group interposed between a oxygroup (—O—) within a carbonyloxy group or an ethereal oxygen atom (—O—)and another ethereal oxygen atom, an acetal structure is formed, and bythe action of acid, the bond between the oxy group within a carbonyloxygroup or the ethereal oxygen atom and the carbon atoms of the(alkyl)methylene group bonded to the oxy group within a carbonyloxygroup or the ethereal oxygen atom is cleaved. Here, the term“(alkyl)methylene group” refers to a methylene group in which a hydrogenatom constituting a methylene group may be substituted with an alkylgroup.

Further, when the carbon atom constituting the ring skeleton of R¹,which has been bonded to the adjacent oxygen atom, has been bonded to analkyl group as a substituent to form a tertiary carbon atom, a tertiaryalkyl ester structure is formed, and by the action of acid, the bondbetween the oxygen atom and the tertiary carbon atom bonded to theoxygen atom is cleaved.

In the case where the structural unit (a0) has the acid decomposableportion, even when the component (A1) consists of the structural unit(a0), the component (A1) can function as a component (A-1).

Specific examples of monomers which derive the structural unit (a0),that is, specific examples of compounds represented by formula (a0),provided that W² represents a group containing a polymerizable group,are shown below. In the formulas, R is the same as defined above.

These compounds can be classified as compounds of the fourth aspect ofthe present invention. The structural units derived from these compoundhave a structure in which the ethylenic double bond portion (CH₂═C(R))is converted into —(CH₂—C(R))—.

As the structural unit (a0) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

In the component (A1), the amount of the structural unit (a0) based onthe combined total of all structural units constituting the component(A1) is preferably 2 to 80 mol %, more preferably 5 to 70 mol %, andstill more preferably 7 to 60 mol %. When the amount of the structuralunit (a0) is at least as large as the lower limit of the above-mentionedrange, the effects obtained by including the structural unit (a0) (e.g.,improvement in lithography properties such as EL, LWR and maskreproducibility, and improvement in residual film ratio at exposedportions of the resist film) are satisfactorily achieved. On the otherhand, when the amount of the structural unit (a0) is no more than theupper limit of the above-mentioned range, a good balance can be reliablyachieved with the other structural units.

When the component (A) contains two or more types of polymeric compounds(resin components), the amount of the structural unit (a0) based on thecombined total of all structural units constituting the component (A) ispreferably 2 to 80 mol %, more preferably 5 to 70 mol %, and still morepreferably 7 to 60 mol %. When the amount of the structural unit (a0) isat least as large as the lower limit of the above-mentioned range, theeffects obtained by including the structural unit (a0) (e.g.,improvement in lithography properties such as EL, LWR and maskreproducibility, and improvement in residual film ratio at exposedportions of the resist film) are satisfactorily achieved. On the otherhand, when the amount of the structural unit (a0) is no more than theupper limit of the above-mentioned range, a good balance can be reliablyachieved with the other structural units.

(Structural Unit (a1))

In the case where the component (A1) is a component (A-1), the component(A1) preferably includes a structural unit (a1) containing an aciddecomposable group that exhibits increased polarity by the action ofacid, in addition to the structural unit (a0).

The aforementioned structural unit (a0) which contains an aciddecomposable group in the structure thereof falls under the definitionof the structural unit (a1); however, such a structural unit is regardedas a structural unit (a0), and does not fall under the definition of thestructural unit (a1).

The term “acid decomposable group” refers to a group in which at least apart of the bond within the structure thereof is cleaved by the actionof acid.

Examples of acid decomposable groups which exhibit increased polarity bythe action of an acid include groups which are decomposed by the actionof acid to form a polar group.

Examples of the polar group include a carboxy group, a hydroxy group, anamino group and a sulfo group (—SO₃H). Among these, a polar groupcontaining —OH in the structure thereof (hereafter, referred to as“OH-containing polar group”) is preferable, a carboxy group or a hydroxygroup is more preferable, and a carboxy group is particularly desirable.

More specifically, as an example of an acid decomposable group, a groupin which the aforementioned polar group has been protected with an aciddissociable group (such as a group in which the hydrogen atom of theOH-containing polar group has been protected with an acid dissociablegroup) can be given.

Here, the “acid dissociable group” includes:

(i) a group in which the bond between the acid dissociable group and theadjacent atom is cleaved by the action of acid; and

(ii) a group in which one of the bonds is cleaved by the action of acid,and then a decarboxylation reaction occurs, thereby cleaving the bondbetween the acid dissociable group and the adjacent atom.

It is necessary that the acid dissociable group that constitutes theacid decomposable group is a group which exhibits a lower polarity thanthe polar group generated by the dissociation of the acid dissociablegroup. Thus, when the acid dissociable group is dissociated by theaction of acid, a polar group exhibiting a higher polarity than that ofthe acid dissociable group is generated, thereby increasing thepolarity. As a result, the polarity of the entire component (A1) isincreased. By the increase in the polarity, the solubility in an alkalideveloping solution changes, and the solubility in an alkali developingsolution is relatively increased, whereas the solubility in an organicdeveloping solution is relatively decreased.

The acid dissociable group is not particularly limited, and any of thegroups that have been conventionally proposed as acid dissociable groupsfor the base resins of chemically amplified resists can be used.

Examples of the acid dissociable group for protecting the carboxy groupor hydroxy group as a polar group include the acid dissociable grouprepresented by general formula (a1-r-1) shown below (hereafter, referredto as “acetal-type acid dissociable group”).

In the formula, Ra′¹ and Ra′² represents a hydrogen atom or an alkylgroup; and Ra′³ represents a hydrocarbon group, provided that Ra′³ maybe bonded to Ra′¹ or Ra′² to form a ring.

In the formula (a1-r-1), it is preferable that at least one of Ra′¹ andRa′² represents a hydrogen atom, and it is more preferable that both ofRa′¹ and Ra′² represent a hydrogen atom.

In the case where Ra′¹ or Ra′² is an alkyl group, as the alkyl group,the same alkyl groups as those described above the for the substituentwhich may be bonded to the carbon atom on the α-position of theaforementioned α-substituted acrylate ester can be mentioned, and analkyl group of 1 to 5 carbon atoms is preferable. Specific examples ofthe alkyl group include linear or branched alkyl groups such as a methylgroup, an ethyl group, a propyl group, an isopropyl group, an n-butylgroup, an isobutyl group, a tert-butyl group, a pentyl group, anisopentyl group and a neopentyl group. Of these, a methyl group or anethyl group is preferable, and a methyl group is particularlypreferable.

In the formula (a1-r-1), examples of the hydrocarbon group for Ra′³include a linear, branched or cyclic alkyl group. The linear alkyl grouppreferably has 1 to 5 carbon atoms, more preferably 1 to 4, and stillmore preferably 1 or 2. Specific examples include a methyl group, anethyl group, an n-propyl group, an n-butyl group and an n-pentyl group.Among these, a methyl group, an ethyl group or an n-butyl group ispreferable, and a methyl group or an ethyl group is more preferable.

The branched alkyl group preferably has 3 to 10 carbon atoms, and morepreferably 3 to 5. Specific examples of such branched alkyl groupsinclude an isopropyl group, an isobutyl group, a tert-butyl group, anisopentyl group and a neopentyl group, and an isopropyl group isparticularly desirable.

The cyclic alkyl group preferably has 3 to 20 carbon atoms, and morepreferably 4 to 12. Specific examples of the cyclic alkyl group includegroups in which one hydrogen atom has been removed from amonocycloalkane such as cyclopentane and cyclohexane; and groups inwhich one hydrogen atom has been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane. In these cyclic alkyl groups, part of the carbonatoms constituting the ring may be replaced with an ethereal oxygen atom(—O—).

In the case where Ra′³ is bonded to Ra′¹ or Ra′² to form a ring, thecyclic group is preferably a 4 to 7-membered ring, and more preferably a4 to 6-membered ring. Specific examples of the cyclic group includetetrahydropyranyl group and tetrahydrofuranyl group.

Examples of the acid dissociable group for protecting the carboxy groupas a polar group include the acid dissociable group represented bygeneral formula (a1-r-2) shown below (hereafter, with respect to theacid dissociable group represented by the following formula (a1-r-2),the acid dissociable group constituted of alkyl groups is referred to as“tertiary ester-type acid dissociable group”).

In the formula, Ra′⁴ to Ra′⁶ each independently represents a hydrocarbongroup, provided that Ra′⁵ and Ra′⁶ may be mutually bonded to form aring.

As the hydrocarbon group for Ra′⁴ to Ra′⁶, the same groups as thosedescribed above for Ra′³ can be mentioned.

Ra′⁴ is preferably an alkyl group of 1 to 5 carbon atoms. In the casewhere Ra′⁵ and Ra′⁶ are mutually bonded to form a ring, a grouprepresented by general formula (a1-r2-1) shown below can be mentioned.On the other hand, in the case where Ra′⁴ to Ra′⁶ are not mutuallybonded and independently represent a hydrocarbon group, the grouprepresented by general formula (a1-r2-2) shown below can be mentioned.

In the formulas, Ra′¹⁰ represents an alkyl group of 1 to 10 carbonatoms; Ra′¹¹ is a group which forms an aliphatic cyclic group togetherwith a carbon atom having Ra′¹⁰ bonded thereto; and Ra′¹² to Ra′¹⁴ eachindependently represents a hydrocarbon group.

In the formula (a1-r2-1), as the alkyl group of 1 to 10 carbon atoms forRa′¹⁰, the same groups as described above for the linear or branchedalkyl group for Ra′³ in the formula (a1-r-1) are preferable. In theformula (a1-r2-1), as the aliphatic cyclic group which is formed byRa′¹¹, the same groups as those described above for the cyclic alkylgroup for Ra′³ in the formula (a1-r-1) are preferable.

In the formula (a1-r2-2), it is preferable that Ra′¹² and Ra′¹⁴ eachindependently represents an alkyl group or 1 to 10 carbon atoms, and itis more preferable that the alkyl group is the same group as thedescribed above for the linear or branched alkyl group for Ra′³ in theformula (a1-r-1), it is still more preferable that the alkyl group is alinear alkyl group of 1 to 5 carbon atoms, and it is particularlypreferable that the alkyl group is a methyl group or an ethyl group.

In the formula (a1-r2-2), it is preferable that Ra′¹³ is the same groupas described above for the linear, branched or cyclic alkyl group forRa′³ in the formula (a1-r-1). Among these, the same cyclic alkyl groupas those describe above for Ra′³ is more preferable.

Specific examples of the formula (a1-r2-1) are shown below.

Specific examples of the formula (a1-r2-2) are shown below.

Examples of the acid dissociable group for protecting a hydroxy group asa polar group include the acid dissociable group represented by generalformula (a1-r-3) shown below (hereafter, referred to as “tertiaryalkyloxycarbonyl-type acid dissociable group”).

In the formula, Ra′⁷ to Ra′⁹ each independently represents an alkylgroup.

In the formula (a1-r-3), Ra′⁷ to Ra′⁹ is preferably an alkyl group of 1to 5 carbon atoms, and more preferably an alkyl group of 1 to 3 carbonatoms.

Further, the total number of carbon atoms within the alkyl group ispreferably 3 to 7, more preferably 3 to 5, and most preferably 3 or 4.

Examples of the structural unit (a1) include a structural unit derivedfrom an acrylate ester which may have the hydrogen atom bonded to thecarbon atom on the α-position substituted with a substituent andcontains an acid decomposable group which exhibits increased polarity bythe action of acid; a structural unit derived from an acrylamide whichcontains an acid decomposable group which exhibits increased polarity bythe action of acid; a structural unit derived from hydroxystyrene or ahydroxystyrene derivative in which at least a part of the hydrogen atomof the hydroxy group is protected with a substituent containing an aciddecomposable group; and a structural unit derived from vinylbenzoic acidor a vinylbenzoic acid derivative in which at least a part of thehydrogen atom within —C(═O)—OH is protected with a substituentcontaining an acid decomposable group.

As the structural unit (a1), a structural unit derived from an acrylateester which may have the hydrogen atom bonded to the carbon atom on theα-position substituted with a substituent is preferable.

Specific examples of preferable structural units for the structural unit(a1) include structural units represented by general formulas (a1-1) and(a1-2) shown below.

In the formulas, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms, a halogenated alkyl group of 1 to 5 carbon atoms, ahydroxyalkyl group, an alkoxy group, —V²¹—COOR⁰″ or —V²¹—OC(═O)R⁰″; Va¹represents a divalent hydrocarbon group which may contain a linkinggroup selected from the group consisting of an ether bond, an urethanebond and an amide bond; n_(a1) each independently represents an integerof 0 to 2; Ra¹ represents an acid dissociable group represented by theaforementioned formula (a1-r-1) or (a1-r-2); Wa¹ represents ahydrocarbon group having a valency of n_(a2)+1; n_(a2) represents aninteger of 1 to 3; and Ra² represents an acid dissociable grouprepresented by the aforementioned formula (a1-r-1) or (a1-r-3).

In the aforementioned formula (a1-1), R is the same as defined for R inthe explanation of the structural unit (a0).

The divalent hydrocarbon group for Va¹ may be either an aliphatichydrocarbon group or an aromatic hydrocarbon group. An “aliphatichydrocarbon group” refers to a hydrocarbon group that has noaromaticity. The aliphatic hydrocarbon group as the divalent hydrocarbongroup for Va¹ may be either saturated or unsaturated. In general, thealiphatic hydrocarbon group is preferably saturated.

As specific examples of the aliphatic hydrocarbon group, a linear orbranched aliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

Further, as the group for Va¹, a group in which the aforementioneddivalent hydrocarbon group has been bonded via an ether bond, urethanebond or amide bond can be mentioned. Va¹ may have one type of linkinggroup or two or more types of linking groups. In the case where the Va¹has two or more linking groups, these linking groups may be the same ordifferent from each other.

The linear or branched aliphatic hydrocarbon group preferably has 1 to10 carbon atoms, more preferably 1 to 6, still more preferably 1 to 4,and most preferably 1 to 3.

As the linear aliphatic hydrocarbon group, a linear alkylene group ispreferable, and specific examples include a methylene group [—CH₂—], anethylene group [—(CH₂)₂—], a trimethylene group [—(CH₂)₃—], atetramethylene group [—(CH₂)₄—] and a pentamethylene group [—(CH₂)₅—].

As the branched aliphatic hydrocarbon group, a branched alkylene groupis preferable, and specific examples include alkylalkylene groups, e.g.,alkylmethylene groups such as —CH(CH₃)—, —CH(CH₂CH₃)—, —C(CH₃)₂—,—C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)—, and —C(CH₂CH₃)₂—; alkylethylenegroups such as —CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂—,—CH(CH₂CH₃)CH₂— and —C(CH₂CH₃)₂—CH₂—; alkyltrimethylene groups such as—CH(CH₃)CH₂CH₂—, and —CH₂CH(CH₃)CH₂—; and alkyltetramethylene groupssuch as —CH(CH₃)CH₂CH₂CH₂—, and —CH₂CH(CH₃)CH₂CH₂—. As the alkyl groupwithin the alkylalkylene group, a linear alkyl group of 1 to 5 carbonatoms is preferable.

As examples of the aliphatic hydrocarbon group containing a ring in thestructure thereof, an alicyclic hydrocarbon group (a group in which twohydrogen atoms have been removed from an aliphatic hydrocarbon ring), agroup in which the alicyclic hydrocarbon group is bonded to the terminalof a linear or branched aliphatic hydrocarbon group, and a group inwhich the alicyclic hydrocarbon group is interposed within a linear orbranched aliphatic hydrocarbon group, can be given. As the linear orbranched aliphatic hydrocarbon group, the same groups as those describedabove can be used.

The alicyclic hydrocarbon group preferably has 3 to 20 carbon atoms, andmore preferably 3 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either a monocyclic group or apolycyclic group. As the monocyclic alicyclic hydrocarbon group, a groupin which 2 hydrogen atoms have been removed from a monocycloalkane ispreferable. The monocycloalkane preferably has 3 to 8 carbon atoms, andspecific examples thereof include cyclopentane, cyclohexane andcyclooctane. As the polycyclic alicyclic group, a group in which twohydrogen atoms have been removed from a polycycloalkane is preferable,and the polycyclic group preferably has 7 to 12 carbon atoms. Examplesof the polycycloalkane include adamantane, norbornane, isobornane,tricyclodecane and tetracyclododecane.

The aromatic hydrocarbon group is a hydrocarbon group having an aromaticring.

The aromatic hydrocarbon group as the divalent hydrocarbon group for Va¹preferably has 5 to 30 carbon atoms, more preferably 5 to 20, still morepreferably 6 to 15, and most preferably 6 to 10. Here, the number ofcarbon atoms within a substituent(s) is not included in the number ofcarbon atoms of the aromatic hydrocarbon group.

Examples of the aromatic ring contained in the aromatic hydrocarbongroup include aromatic hydrocarbon rings, such as benzene, biphenyl,fluorene, naphthalene, anthracene and phenanthrene; and aromatic heterorings in which part of the carbon atoms constituting the aforementionedaromatic hydrocarbon rings has been substituted with a hetero atom.Examples of the hetero atom within the aromatic hetero rings include anoxygen atom, a sulfur atom and a nitrogen atom.

Specific examples of the aromatic hydrocarbon group include a group inwhich two hydrogen atoms have been removed from the aforementionedaromatic hydrocarbon ring (arylene group); and a group in which onehydrogen atom has been removed from the aforementioned aromatichydrocarbon ring (aryl group) and one hydrogen atom thereof has beensubstituted with an alkylene group (for example, a group in which onehydrogen atom has been removed from an aryl group within an arylalkylgroup such as a benzyl group, a phenethyl group, a 1-naphthylmethylgroup, a 2-naphthylmethyl group, a 1-naphthylethyl group, or a2-naphthylethyl group). The alkylene group (alkyl chain within thearylalkyl group) preferably has 1 to 4 carbon atoms, more preferably 1or 2, and most preferably 1.

In the aforementioned formula (a1-2), the hydrocarbon group for Wa¹having a valency of n_(a2)+1 may be either an aliphatic hydrocarbongroup or an aromatic hydrocarbon group. The aliphatic cyclic grouprefers to a hydrocarbon group that has no aromaticity, and may be eithersaturated or unsaturated, but is preferably saturated. Examples of thealiphatic hydrocarbon group include a linear or branched aliphatichydrocarbon group, an aliphatic hydrocarbon group containing a ring inthe structure thereof, and a combination of the linear or branchedaliphatic hydrocarbon group and the aliphatic hydrocarbon groupcontaining a ring in the structure thereof. As the specific examplesthereof, the same groups as those described above for Va¹ in theaforementioned formula (a1-1) can be mentioned.

The valency of n_(a2)+1 is preferably divalent, trivalent ortetravalent, and divalent or trivalent is more preferable.

As the structural unit represented by the aforementioned formula (a1-2),a structural unit represented by general formula (a1-2-01) shown belowis desirable.

In the formula (a1-2-01), Ra² represents an acid dissociable grouprepresented by the aforementioned formula (a1-r-1) or (a1-r-3); n_(a2)is an integer of 1 to 3, preferably 1 or 2, and more preferably 1; c isan integer of 0 to 3, preferably 0 or 1, and more preferably 1; and R isthe same as defined above.

Specific examples of the structural unit (a1-1) are shown below.

Specific examples of the structural unit (a1-2) are shown below.

As the structural unit (a1) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

In the component (A1), the amount of the structural unit (a1) based onthe combined total of all structural units constituting the component(A1) is preferably 20 to 80 mol %, more preferably 20 to 75 mol %, andstill more preferably 25 to 70 mol %. When the amount of the structuralunit (a1) is at least as large as the lower limit of the above-mentionedrange, a pattern can be easily formed, and various lithographyproperties such as sensitivity, resolution, LWR and the like areimproved. On the other hand, when the amount of the structural unit (a1)is no more than the upper limit of the above-mentioned range, a goodbalance can be achieved with the other structural units.

(Other Structural Units)

The component (A1) may be further include a structural unit other thanthe structural units (a0) and (a1), as well as the structural units (a0)and (a1). As the other structural unit, any other structural unit whichcannot be classified as the aforementioned structural units can be usedwithout any particular limitation, and any of the multitude ofconventional structural units used within resist resins for ArF excimerlasers or KrF excimer lasers (and particularly for ArF excimer lasers)can be used. For example, a structural units (a2) to (a4) shown belowcan be used.

Structural Unit (a2):

The structural unit (a2) is a structural unit which contains alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group, and which does not fall under thedefinition of the structural unit (a0).

When the component (A1) is used for forming a resist film, thelactone-containing cyclic group, the —SO₂— containing cyclic group orthe carbonate-containing cyclic group within the structural unit (a2) iseffective in improving the adhesion between the resist film and thesubstrate.

As the lactone-containing cyclic group, the —SO₂— containing cyclicgroup and the carbonate-containing cyclic group within the structuralunit (a2), the same as those described above in the explanation of R¹ inthe general formula (a0) can be mentioned.

The aforementioned structural unit (a1) which contains alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group falls under the definition of thestructural unit (a2); however, such a structural unit is regarded as astructural unit (a1), and does not fall under the definition of thestructural unit (a2).

The structural unit (a2) is preferably a structural unit represented bygeneral formula (a2-1) shown below.

In the formula, R represents a hydrogen atom, an alkyl group of 1 to 5carbon atoms, a halogenated alkyl group of 1 to 5 carbon atoms, ahydroxyalkyl group, an alkoxy group, —V²¹—COOR⁰″, or —OC(═O)R⁰″; Ya²¹represents a single bond or a divalent linking group; La²¹ represents—O—, —COO—, —CON(R′)—, —COO—, —CONHCO— or —CONHCS; and R′ represents ahydrogen atom or a methyl group, provided that, when La²¹ represents—O—, Ya²¹ does not represents —CO—; Ra²¹ represents a lactone-containingcyclic group, a carbonate-containing cyclic group or an —SO₂— containingcyclic group; V²¹ represents a single bond or an alkylene group; and R⁰″represents a hydrogen atom, a hydrocarbon group which may have asubstituent, or an anion group.

In the formula (a2-1), R are the same as defined above.

The divalent linking group for Ya²¹ is not particularly limited, andpreferable examples thereof include a divalent hydrocarbon group whichmay have a substituent and a divalent linking group containing a heteroatom.

(Divalent Hydrocarbon Group which May have a Substituent)

The hydrocarbon group as a divalent linking group may be either analiphatic hydrocarbon group or an aromatic hydrocarbon group.

An “aliphatic hydrocarbon group” refers to a hydrocarbon group that hasno aromaticity. The aliphatic hydrocarbon group may be saturated orunsaturated. In general, the aliphatic hydrocarbon group is preferablysaturated.

Examples of the aliphatic hydrocarbon group include a linear or branchedaliphatic hydrocarbon group, and an aliphatic hydrocarbon groupcontaining a ring in the structure thereof can be given.

Specific examples of the linear or branched aliphatic hydrocarbon groupinclude the same group as exemplified above for Va¹ in theaforementioned formula (a1-1).

The linear or branched aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include a fluorine atom, afluorinated alkyl group of 1 to 5 carbon atoms, and a carbonyl group.

As examples of the hydrocarbon group containing a ring in the structurethereof, a cyclic aliphatic hydrocarbon group which may have asubstituent containing a hetero atom (a group in which two hydrogenatoms have been removed from an aliphatic hydrocarbon ring) in the ringstructure thereof, a group in which the cyclic aliphatic hydrocarbongroup is bonded to the terminal of a linear or branched aliphatichydrocarbon group, and a group in which the cyclic aliphatic group isinterposed within a linear or branched aliphatic hydrocarbon group, canbe given. As the linear or branched aliphatic hydrocarbon group, thesame groups as those described above can be used.

The cyclic aliphatic hydrocarbon group preferably has 3 to 20 carbonatoms, and more preferably 3 to 12 carbon atoms.

Specific examples of the cyclic aliphatic hydrocarbon group include thesame group as exemplified above for Va¹ in the aforementioned formula(a1-1).

The cyclic aliphatic hydrocarbon group may or may not have asubstituent. Examples of the substituent include an alkyl group, analkoxy group, a halogen atom, a halogenated alkyl group, a hydroxylgroup and a carbonyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Examples of the halogenated alkyl group for the substituent includegroups in which part or all of the hydrogen atoms within theaforementioned alkyl groups has been substituted with the aforementionedhalogen atoms.

In the cyclic aliphatic hydrocarbon group, part of the carbon atomsconstituting the ring structure thereof may be substituted with asubstituent containing a hetero atom. The substituent containing ahetero atom is preferably —O—, —C(═O)—O—, —S—, —S(═O)₂—, or —S(═O)₂—O—

Specific examples of the aromatic hydrocarbon group as a divalenthydrocarbon group include the same group as exemplified above for Va¹ inthe aforementioned formula (a1-1).

With respect to the aromatic hydrocarbon group, the hydrogen atom withinthe aromatic hydrocarbon group may be substituted with a substituent.For example, the hydrogen atom bonded to the aromatic ring within thearomatic hydrocarbon group may be substituted with a substituent.Examples of substituents include an alkyl group, an alkoxy group, ahalogen atom, a halogenated alkyl group, and a hydroxyl group.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

As the alkoxy group, the halogen atom and the halogenated alkyl groupfor the substituent, the same groups as the aforementioned substituentgroups for substituting a hydrogen atom within the cyclic aliphatichydrocarbon group can be used.

(Divalent Linking Group Containing a Hetero Atom)

With respect to a divalent linking group containing a hetero atom, ahetero atom is an atom other than carbon and hydrogen, and examplesthereof include an oxygen atom, a nitrogen atom, a sulfur atom and ahalogen atom.

In the case where Ya²¹ represents a divalent linking group containing ahetero atom, preferable examples of the linking group include —O—,—C(═O)—O—, —C(═O)—, —O—C(═O)—O—, —C(═O)—NH—, —NH—, —NH—C(═NH)— (whereinH may be substituted with a substituent such as an alkyl group or anacyl group), —S—, —S(═O)₂—, —S(═O)₂—O— and a group represented bygeneral formula —Y²¹—O—Y²²—, —Y^(<)—O—, —Y²¹—C(═O)—O—,—[Y²¹—C(═O)—O]_(m′)—Y²²— or —Y²¹—O—C(═O)—²²— [in the formulas, each ofY²¹ and Y²² independently represents a divalent hydrocarbon group whichmay have a substituent, O represents an oxygen atom, and m′ representsan integer of 0 to 3].

The divalent linking group containing a hetero atom represents—C(═O)—NH—, —NH—, or —NH—C(═NH)—, H may be substituted with asubstituent such as an alkyl group, an acyl group or the like. Thesubstituent (an alkyl group, an acyl group or the like) preferably has 1to 10 carbon atoms, more preferably 1 to 8, and most preferably 1 to 5.

In formula —Y²¹—O—Y²²—, —Y²¹—O—, —Y²¹—C(═O)—O—, —[Y²¹—C(═O)—O]_(m′)—Y²²—or —Y²¹—O—C(═O)—Y²²—, Y²¹ and Y²² each independently represents adivalent hydrocarbon group which may have a substituent. Examples of thedivalent hydrocarbon group include the same groups as those describedabove as the “divalent hydrocarbon group which may have a substituent”in the explanation of the aforementioned divalent linking group.

As Y²¹, a linear aliphatic hydrocarbon group is preferable, morepreferably a linear alkylene group, still more preferably a linearalkylene group of 1 to 5 carbon atoms, and a methylene group or anethylene group is particularly desirable.

As Y²², a linear or branched aliphatic hydrocarbon group is preferable,and a methylene group, an ethylene group or an alkylmethylene group ismore preferable. The alkyl group within the alkylmethylene group ispreferably a linear alkyl group of 1 to 5 carbon atoms, more preferablya linear alkyl group of 1 to 3 carbon atoms, and most preferably amethyl group.

In the group represented by the formula —[Y²¹—C(═O)—O]_(m′—Y) ²²—, m′represents an integer of 0 to 3, preferably an integer of 0 to 2, morepreferably 0 or 1, and particularly preferably 1. Namely, it isparticularly desirable that the group represented by the formula—[Y²¹—C(═O)—O]_(m′)—Y²²— is a group represented by the formula—Y²¹—C(═O)—O—Y²²—. Among these, a group represented by the formula—(CH₂)_(a′)—C(═O)—O—(CH₂)_(b′)— is preferable. In the formula, a′ is aninteger of 1 to 10, preferably an integer of 1 to 8, more preferably aninteger of 1 to 5, still more preferably 1 or 2, and most preferably 1.b′ is an integer of 1 to 10, preferably an integer of 1 to 8, morepreferably an integer of 1 to 5, still more preferably 1 or 2, and mostpreferably 1.

Ya²¹ preferably represents an ester bond [—C(═O)—O—], an ether bond(—O—), a linear or branched alkylene group, a combination of these, or asingle bond.

In the formula (a2-1), Ra²¹ represents a lactone-containing cyclicgroup, an —SO₂-containing cyclic group or a carbonate-containing cyclicgroup.

As the lactone-containing cyclic group, the —SO₂— containing cyclicgroup and the carbonate-containing cyclic group for Ra²¹, the samegroups as those described above in the explanation of R¹ in the generalformula (a0) can be mentioned.

As the structural unit (a2) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the component (A1) contains the structural unit (a2), the amount ofthe structural unit (a2) based on the combined total of all structuralunits constituting the component (A1) is preferably 1 to 80 mol %, morepreferably 10 to 70 mol %, still more preferably 10 to 65 mol %, andparticularly preferably 10 to 60 mol %. When the amount of thestructural unit (a2) is at least as large as the lower limit of theabove-mentioned range, the effect of using the structural unit (a2) canbe satisfactorily achieved. On the other hand, when the amount of thestructural unit (a2) is no more than the upper limit of theabove-mentioned range, a good balance can be achieved with the otherstructural units, and various lithography properties such as DOF and CDUand pattern shape can be improved.

Structural Unit (a3):

The structural unit (a3) is a structural unit containing a polargroup-containing aliphatic hydrocarbon group (provided that thestructural units that fall under the definition of structural units(a1), (a0) and (a2) are excluded).

When the component (A1) includes the structural unit (a3), it ispresumed that the hydrophilicity of the component (A1) is enhanced,thereby contributing to improvement in resolution.

Examples of the polar group include a hydroxyl group, a cyano group, acarboxyl group, or a hydroxyalkyl group in which part of the hydrogenatoms of the alkyl group have been substituted with fluorine atoms,although a hydroxyl group is particularly desirable.

Examples of the aliphatic hydrocarbon group include linear or branchedhydrocarbon groups (preferably alkylene groups) of 1 to 10 carbon atoms,and cyclic aliphatic hydrocarbon groups (cyclic groups). These cyclicgroups may be monocyclic or polycyclic, and can be selectedappropriately from the multitude of groups that have been proposed forthe resins of resist compositions designed for use with ArF excimerlasers. The cyclic group is preferably a polycyclic group, morepreferably a polycyclic group of 7 to 30 carbon atoms.

Of the various possibilities, structural units derived from an acrylateester that includes an aliphatic polycyclic group that contains ahydroxyl group, a cyano group, a carboxyl group or a hydroxyalkyl groupin which part of the hydrogen atoms of the alkyl group have beensubstituted with fluorine atoms are particularly desirable. Examples ofthe polycyclic group include groups in which two or more hydrogen atomshave been removed from a bicycloalkane, tricycloalkane, tetracycloalkaneor the like. Specific examples include groups in which two or morehydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane. Of these polycyclic groups, groups in which two ormore hydrogen atoms have been removed from adamantane, norbornane ortetracyclododecane are preferred industrially.

As the structural unit (a3), there is no particular limitation as longas it is a structural unit containing a polar group-containing aliphatichydrocarbon group, and an arbitrary structural unit may be used.

The structural unit (a3) is preferably a structural unit derived from anacrylate ester which may have the hydrogen atom bonded to the carbonatom on the α-position substituted with a substituent and contains apolar group-containing aliphatic hydrocarbon group.

When the aliphatic hydrocarbon group within the polar group-containingaliphatic hydrocarbon group is a linear or branched hydrocarbon group of1 to 10 carbon atoms, the structural unit (a3) is preferably astructural unit derived from a hydroxyethyl ester of acrylic acid. Onthe other hand, when the hydrocarbon group is a polycyclic group,structural units represented by formulas (a3-1), (a3-2) and (a3-3) shownbelow are preferable.

In the formulas, R is as defined above; j is an integer of 1 to 3; k isan integer of 1 to 3; t′ is an integer of 1 to 3; 1 is an integer of 1to 5; and s is an integer of 1 to 3.

In formula (a3-1), j is preferably 1 or 2, and more preferably 1. When jis 2, it is preferable that the hydroxyl groups be bonded to the 3rd and5th positions of the adamantyl group. When j is 1, it is preferable thatthe hydroxyl group be bonded to the 3rd position of the adamantyl group.

j is preferably 1, and it is particularly desirable that the hydroxylgroup be bonded to the 3rd position of the adamantyl group.

In formula (a3-2), k is preferably 1. The cyano group is preferablybonded to the 5th or 6th position of the norbornyl group.

In formula (a3-3), t′ is preferably 1. 1 is preferably 1. s ispreferably 1. Further, in formula (a3-3), it is preferable that a2-norbonyl group or 3-norbonyl group be bonded to the terminal of thecarboxy group of the acrylic acid. The fluorinated alkyl alcohol ispreferably bonded to the 5th or 6th position of the norbornyl group.

As the structural unit (a3) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the component (A1) contains the structural unit (a3), the amount ofthe structural unit (a3) within the component (A1) based on the combinedtotal of all structural units constituting the component (A1) ispreferably 5 to 50 mol %, more preferably 5 to 40 mol %, and still morepreferably 5 to 25 mol %. When the amount of the structural unit (a3) isat least as large as the lower limit of the above-mentioned range, theeffect of using the structural unit (a3) can be satisfactorily achieved.On the other hand, when the amount of the structural unit (a3) is nomore than the upper limit of the above-mentioned range, a good balancecan be achieved with the other structural units.

Structural Unit (a4):

The structural unit (a1) is a structural unit containing an acidnon-dissociable, aliphatic cyclic group.

When the component (A1) includes the structural unit (a1), dry etchingresistance of the resist pattern to be formed is improved. Further, thehydrophobicity of the component (A1) is further improved. Increase inthe hydrophobicity contributes to improvement in terms of resolution,shape of the resist pattern and the like, particularly in an organicsolvent developing process.

An “acid non-dissociable, aliphatic cyclic group” in the structural unit(a4) refers to a cyclic group which is not dissociated by the action ofthe acid (e.g., acid generated from the component (B) described later)upon exposure, and remains in the structural unit.

As the structural unit (a4), a structural unit which contains anon-acid-dissociable aliphatic cyclic group, and is also derived from anacrylate ester is preferable. Examples of this cyclic group include thesame groups as those described above in relation to the aforementionedstructural unit (a1), and any of the multitude of conventional groupsused within the resin component of resist compositions for ArF excimerlasers or KrF excimer lasers (and particularly for ArF excimer lasers)can be used.

In consideration of industrial availability and the like, at least onepolycyclic group selected from amongst a tricyclodecyl group, adamantylgroup, tetracyclododecyl group, isobornyl group, and norbornyl group isparticularly desirable. These polycyclic groups may be substituted witha linear or branched alkyl group of 1 to 5 carbon atoms.

Specific examples of the structural unit (a4) include structural unitswith structures represented by general formulas (a4-1) to (a4-6) shownbelow.

In the formulas, R^(α) is the same as defined above.

As the structural unit (a4) contained in the component (A1), 1 type ofstructural unit may be used, or 2 or more types may be used.

When the component (A1) includes the structural unit (a4), the amount ofthe structural unit (a4) based on the combined total of all structuralunits constituting the component (A1) is preferably 1 to 30 mol %, andmore preferably 3 to 20 mol %.

The component (A1) is a polymeric compound including at least thestructural unit (a0).

The component (A1) is preferably a copolymer containing the structuralunits (a0) and (a1). Examples of such copolymers include a copolymerconsisting of the structural units (a0) and (a1), a copolymer consistingof the structural units (a0), (a1) and (a2), a copolymer consisting ofthe structural units (a0), (a1) and (a3), and a copolymer consisting ofthe structural units (a0), (a1), (a2) and (a3).

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (A1)is not particularly limited, but is preferably 1,000 to 50,000, morepreferably 1,500 to 30,000, and most preferably 2,000 to 20,000. Whenthe weight average molecular weight is no more than the upper limit ofthe above-mentioned range, the resist composition exhibits asatisfactory solubility in a resist solvent. On the other hand, when theweight average molecular weight is at least as large as the lower limitof the above-mentioned range, dry etching resistance and thecross-sectional shape of the resist pattern becomes satisfactory.

Further, the dispersity (Mw/Mn) is not particularly limited, but ispreferably 1.0 to 5.0, more preferably 1.0 to 3.0, and most preferably1.0 to 2.5. Here, Mn is the number average molecular weight.

The component (A1) can be obtained, for example, by a conventionalradical polymerization or the like of the monomers corresponding witheach of the structural units, using a radical polymerization initiatorsuch as azobisisobutyronitrile (AIBN) or dimethyl2,2′-azobis(isobutyrate).

Furthermore, in the component (A1), by using a chain transfer agent suchas HS—CH₂—CH₂—CH₂—C(CF₃)₂—OH, a —C(CF₃)₂—OH group can be introduced atthe terminals of the component (A1). Such a copolymer having introduceda hydroxyalkyl group in which some of the hydrogen atoms of the alkylgroup are substituted with fluorine atoms is effective in reducingdeveloping defects and LER (line edge roughness: unevenness of the sidewalls of a line pattern).

The production method of the monomer which derives the structural unit(a0) will be described later with respect to a compound of fourth aspectof the present invention. As the monomers which yield the arbitrarystructural units, commercially available monomers may be used, or themonomers may be synthesized by a conventional method.

As the component (A1), one type may be used alone, or two or more typesmay be used in combination.

In the component (A), the amount of the component (A1) based on thetotal weight of the component (A) is preferably 25% by weight or more,more preferably 50% by weight or more, still more preferably 75% byweight or more, and may be even 100% by weight. When the amount of thecomponent (A1) is 25% by weight or more, various lithography propertiesare improved, such as improvement in MEF and circularity, and reductionof roughness.

In the resist composition of the present invention, the component (A)may contain “a base component which exhibits increased polarity underaction of acid” other than the component (A1) (hereafter, referred to as“component (A2)”).

The component (A2) is not particularly limited, and any of the multitudeof conventional base components used within chemically amplified resistcompositions (e.g., base resins used within chemically amplified resistcompositions for ArF excimer lasers or KrF excimer lasers, preferablyArF excimer lasers) can be used. For example, as a base resin for ArFexcimer laser, a base resin having the aforementioned structural unit(a1) as an essential component, and optionally the aforementionedstructural units (a2) to (a4) can be used.

As the component (A2), one type of resin may be used, or two or moretypes of resins may be used in combination.

In the resist composition of the present invention, as the component(A), one type may be used, or two or more types may be used incombination.

In the resist composition of the present invention, the amount of thecomponent (A) can be appropriately adjusted depending on the thicknessof the resist film to be formed, and the like.

<Component (B)>

Furthermore, the resist composition of the present invention may includea component (B) (i.e., an acid generator component which generates acidupon exposure), in addition to the component (A).

As the component (B), there is no particular limitation, and any of theknown acid generators used in conventional chemically amplified resistcompositions can be used. Examples of these acid generators arenumerous, and include onium salt acid generators such as iodonium saltsand sulfonium salts; oxime sulfonate acid generators; diazomethane acidgenerators such as bisalkyl or bisaryl sulfonyl diazomethanes andpoly(bis-sulfonyl)diazomethanes; nitrobenzylsulfonate acid generators;iminosulfonate acid generators; and disulfone acid generators.

As an onium salt acid generator, a compound represented by generalformula (b-1) or (b-2) shown below can be used.

In the formulas, R¹⁰¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent, or achain-like alkenyl group which may have a substituent; Y¹⁰¹ represents asingle bond or a divalent linking group containing an oxygen atom; V¹⁰¹represents a single bond, an alkylene group or a fluorinated alkylenegroup; R¹⁰² represents a fluorine atom or a fluorinated alkyl group of 1to 5 carbon atoms; R¹⁰⁴ and R¹⁰⁵ each independently represents an alkylgroup of 1 to 10 carbon atoms or a fluorinated alkyl group of 1 to 10carbon atoms, and may be mutually bonded to form a ring; and M^(m+)represents an organic cation having a valency of m.

{Anion Moiety}

In the formula (b-1), R¹⁰¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent.

The cyclic group is preferably a cyclic hydrocarbon group, and thecyclic hydrocarbon group may be either an aromatic hydrocarbon group oran aliphatic hydrocarbon group.

As the aromatic hydrocarbon group for R¹⁰¹, groups in which one hydrogenatom has been removed from an aromatic hydrocarbon ring described abovein relation to the divalent aromatic hydrocarbon group for Va¹ in theformula (a1-1) or an aromatic compound containing two or more aromaticring can be mentioned, and a phenyl group or a naphthyl group ispreferable.

As the cyclic aliphatic hydrocarbon group for R¹⁰¹, groups in which onehydrogen atom has been removed from a monocycloalkane or apolycycloalkane exemplified above in the explanation of the divalentaliphatic hydrocarbon group for Va¹ in the formula (a1-1) can bementioned, and an adamantyl group or a norbornyl group is preferable.

Further, the cyclic hydrocarbon group for R¹⁰¹ may contain a hetero atomlike as a heterocycle, and specific examples thereof includelactone-containing cyclic groups represented by the aforementionedgeneral formulas (a2-r-1) to (a2-r-7), —SO₂— containing cyclic groupsrepresented by the aforementioned formulas (a5-r-1) to (a5-r-4) andheterocycles shown below.

As the substituent for the cyclic hydrocarbon group for R¹⁰¹, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group or the like can be used.

The alkyl group as the substituent is preferably an alkyl group of 1 to5 carbon atoms, and a methyl group, an ethyl group, a propyl group, ann-butyl group or a tert-butyl group is most desirable.

The alkoxy group as the substituent is preferably an alkoxy group having1 to 5 carbon atoms, more preferably a methoxy group, an ethoxy group,an n-propoxy group, an iso-propoxy group, an n-butoxy group or atert-butoxy group, and most preferably a methoxy group or an ethoxygroup.

Examples of the halogen atom for the substituent include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is preferable.

Example of the aforementioned halogenated alkyl group includes a groupin which a part or all of the hydrogen atoms within an alkyl group of 1to 5 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group,an n-butyl group or a tert-butyl group) have been substituted with theaforementioned halogen atoms.

The chain-like alkyl group for R¹⁰¹ may be linear or branched. Thelinear alkyl group preferably has 1 to 20 carbon atoms, more preferably1 to 15, and most preferably 1 to 10. Specific examples include a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a nonyl group, a decylgroup, an undecyl group, a dodecyl group, a tridecyl group, anisotridecyl group, a tetradecyl group, a pentadecyl group, a hexadecylgroup, an isohexadecyl group, a heptadecyl group, an octadecyl group, anonadecyl group, an icosyl group, a henicosyl group and a docosyl group.

The branched alkyl group preferably has 3 to 20 carbon atoms, morepreferably 3 to 15, and most preferably 3 to 10. Specific examplesinclude a 1-methylethyl group, a 1-methylpropyl group, a 2-methylpropylgroup, a 1-methylbutyl group, a 2-methylbutyl group, a 3-methylbutylgroup, a 1-ethylbutyl group, a 2-ethylbutyl group, a 1-methylpentylgroup, a 2-methylpentyl group, a 3-methylpentyl group and a4-methylpentyl group.

The chain-like alkenyl group for R¹⁰¹ may be linear or branched, andpreferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbonatoms, still more preferably 2 to 4 carbon atoms, and particularlypreferably 3 carbon atoms. Examples of linear alkenyl groups include avinyl group, a propenyl group (an allyl group) and a butynyl group.Examples of branched alkenyl groups include a 1-methylpropenyl group anda 2-methylpropenyl group.

Among the above-mentioned examples, as the chain-like alkenyl group, apropenyl group is particularly desirable.

As the substituent for the chain-like alkyl group or alkenyl group forR¹⁰¹, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxyl group, a carbonyl group, a nitro group, an amino group, acyclic group for R¹⁰¹ or the like can be used.

In the present invention, R¹⁰¹ is preferably a cyclic hydrocarbon groupwhich may have a substituent, and a phenyl group, a naphthyl group, agroup in which one or more hydrogen atoms have been removed from apolycycloalkane, lactone-containing cyclic groups represented by theformulas (a2-r-1) to (a2-r-7), —SO₂— containing cyclic groupsrepresented by the formulas (a5-r-1) to (a5-r-4) or the like arepreferable.

In the case where Y¹⁰¹ is a divalent linking group containing an oxygenatom, R¹⁰¹ may contain an atom other than an oxygen atom. Examples ofatoms other than an oxygen atom include a carbon atom, a hydrogen atom,a sulfur atom and a nitrogen atom.

Examples of divalent linkage groups containing an oxygen atom includenon-hydrocarbon, oxygen atom-containing linkage groups such as an oxygenatom (an ether bond; —O—), an ester bond (—C(═O)—O—), an amide bond(—C(═O)—NH—), a carbonyl group (—C(═O)—) and a carbonate group(—O—C(═O)—O—); and a combination of any of the aforementionednon-hydrocarbon, oxygen atom-containing linkage groups with an alkylenegroup. Furthermore, the combinations may have a sulfonyl group (—SO₂—)bonded thereto. As the combination, the linking group represented byformulas (y-a1-1) to (y-a1-7) shown below can be mentioned.

In the formulas, V′¹⁰¹ represents a single bond or an alkylene group of1 to 5 carbon atoms; V′¹⁰² represents a divalent saturated hydrocarbongroup of 1 to 30 carbon atoms.

The divalent saturated hydrocarbon group for V′¹⁰² is preferably analkylene group of 1 to 30 carbon atoms.

Specific examples of the alkylene group for V′¹⁰¹ and V′¹⁰² include amethylene group [—CH₂—]; alkylmethylene groups such as —CH(CH₃)—,—CH(CH₂CH₃)—, —C(CH₃)₂—, —C(CH₃)(CH₂CH₃)—, —C(CH₃)(CH₂CH₂CH₃)— and—C(CH₂CH₃)₂—; an ethylene group [—CH₂CH₂—]; alkylethylene groups such as—CH(CH₃)CH₂—, —CH(CH₃)CH(CH₃)—, —C(CH₃)₂CH₂— and —CH(CH₂CH₃)CH₂—; atrimethylene group (n-propylene group)[—CH₂CH₂CH₂—]; alkyltrimethylenegroups such as —CH(CH₃)CH₂CH₂— and —CH₂CH(CH₃)CH₂—; a tetramethylenegroup [—CH₂CH₂CH₂CH₂—]; alkyltetramethylene groups such as—CH(CH₃)CH₂CH₂CH₂— and —CH₂CH(CH₃)CH₂CH₂—; and a pentamethylene group[—CH₂CH₂CH₂CH₂CH₂—]. Among these, a linear alkylene group is preferable.

Further, part of methylene group within the alkylene group for V′¹⁰¹ andV′¹⁰² may be substituted with a divalent aliphatic cyclic group of 5 to10 carbon atoms. The aliphatic cyclic group is preferably a divalentgroup in which one hydrogen atom has been removed from the cyclic alkylgroup for Ra′³, and a cyclohexylene group, 1,5-adamantylene group or2,6-adamantylene group is preferable.

Y¹⁰¹ is preferably a divalent linking group containing an ether bond oran ester bond, and groups represented by the aforementioned formulas(y-a1-1) to (y-a1-5) are preferable.

In the formula (b-1), V¹⁰¹ is preferably a single bond or a fluorinatedalkylene group of 1 to 4 carbon atoms.

In the formula (b-1), R¹⁰² is preferably a fluorine atom or aperfluoroalkyl group of 1 to 5 carbon atoms, and is more preferably afluorine atom.

As specific examples of anion moieties of the formula (b-1),

fluorinated alkylsulfonate anions such as a trifluoromethanesulfonateanion or a perfluorobutanesulfonate anion when Y¹⁰¹ is a single bond,and

anions represented by formula (an-1) to (an-3) shown below when Y¹⁰¹ isa divalent linking group containing an oxygen atom can be mentioned.

In the formulas, R″¹⁰¹ represents an aliphatic cyclic group which mayhave a substituent, a group represented by any one of the aforementionedformulas (r-hr-1) to (r-hr-6) or a chain-like alkyl group which may havea substituent; R″¹⁰² represents an aliphatic cyclic group which may havea substituent, a lactone-containing cyclic group represented by any oneof the aforementioned formulas (a2-r-1) to (a2-r-7) or an—SO₂-containing cyclic group represented by any one of theaforementioned formulas (a5-r-1) to (a5-r-4); R″¹⁰³ represents anaromatic cyclic group which may have a substituent, an aliphatic cyclicgroup which may have a substituent or a chain-like alkenyl group whichmay have a substituent; v″ represents an integer of 0 to 3; q″represents an integer of 1 to 20; t″ represents an integer of 1 to 3;and n″ represents 0 or 1.

As the aliphatic cyclic group for R″¹⁰¹, R″¹⁰² and R″¹⁰³ which may havea substituent, the same groups as the cyclic aliphatic hydrocarbon groupfor R¹⁰¹ described above are preferable.

As the substituent, the same groups as those described above forsubstituting the cyclic aliphatic hydrocarbon group for R¹⁰¹ can bementioned.

As the aromatic cyclic group for R″¹⁰³ which may have a substituent, thesame groups as the cyclic aromatic hydrocarbon group for R¹⁰¹ describedabove are preferable.

As the substituent, the same groups as those described above forsubstituting the cyclic aromatic hydrocarbon group for R¹⁰¹ can bementioned.

As the chain-like alkyl group for R″¹⁰¹ which may have a substituent,the same groups as those described above for R¹⁰¹ are preferable. As thechain-like alkenyl group for R″¹⁰³ which may have a substituent, thesame groups as those described above for R¹⁰¹ are preferable.

In the formula (b-2), R¹⁰⁴ and R¹⁰⁵ each independently represents analkyl group of 1 to 10 carbon atoms or a fluorinated alkyl group of 1 to10 carbon atoms, and may be mutually bonded to form a ring.

R¹⁰⁴ and R¹⁰⁵ are preferably linear or branched (fluorinated) alkylgroups. The (fluorinated) alkyl group has 1 to 10 carbon atoms,preferably 1 to 7, and more preferably 1 to 3. The smaller the number ofcarbon atoms of the (fluorinated) alkyl group for R¹″ and R¹⁰⁵ withinthe above-mentioned range of the number of carbon atoms, the more thesolubility in a resist solvent is improved.

Further, in the (fluorinated) alkyl group for R¹⁰⁴ and R¹⁰⁵, it ispreferable that the number of hydrogen atoms substituted with fluorineatoms is as large as possible because the acid strength increases andthe transparency to high energy radiation of 200 nm or less or electronbeam is improved.

The fluorination ratio of the (fluorinated) alkyl group is preferablyfrom 70 to 100%, more preferably from 90 to 100%, and it is particularlydesirable that the (fluorinated) alkyl group be a perfluoroalkyl groupin which all hydrogen atoms are substituted with fluorine atoms.

Here, the “(fluorinated) alkyl group” refers to an alkyl group in whichpart or all the hydrogen atoms constituting the alkyl group may besubstituted with a fluorine atom.

{Cation Moiety}

In formulas (b-1) and (b-2), M^(m+) represents an organic cation havinga valency of m. The organic cation is not particularly limited, and anorganic cation conventionally known as the cation moiety of an oniumsalt acid generator for a resist composition can be used. Among these, asulfonium cation or an iodonium cation is preferable, and cationmoieties represented by general formulas (ca-1) to (ca-4) show below areparticularly preferable.

In the formulas, R²⁰¹ to R²⁰⁷, R²¹¹ and R²¹² each independentlyrepresents an aryl group which may have a substituent, an alkyl groupwhich may have a substituent or an alkenyl group which may have asubstituent, provided that R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ andR²¹² may be mutually bonded to form a ring with the sulfur atom; R²⁰⁸and R²⁰⁹ each independently represents a hydrogen atom, or an alkylgroup of 1 to 5 carbon atoms; R²¹⁰ represents an aryl group which mayhave a substituent, an alkyl group which may have a substituent, analkenyl group which may have a substituent or an —SO₂— containing cyclicgroup which may have a substituent; L²⁰¹ represents —C(═O)— or —C(═O)O—;Y²⁰¹ each independently represents an arylene group, an alkylene groupor an alkenylene group; x represents 1 or 2; and W²⁰¹ represents alinking group having a valency of (x+1).

As the aryl group for R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹², an unsubstitutedaryl group of 6 to 20 carbon atoms can be mentioned, and a phenyl groupor a naphthyl group is preferable.

As the alkyl group for R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹², a chain-like orcyclic alkyl group of 1 to 30 carbon atoms is preferable.

The alkenyl group for R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹² preferably has 2 to10 carbon atoms.

R²⁰⁸ and R²⁰⁹ is preferably a hydrogen atom or an alkyl group of 1 to 3carbon atoms, and when R²⁰⁸ and R²⁰⁹ each represents an alkyl group,R²⁰⁸ and R²⁰⁹ may be mutually bonded to form a ring.

As the —SO₂— containing cyclic group for R²¹⁰ which may have asubstituent, the same groups as those described above for Ra²¹ can bementioned, and the group represented by the aforementioned generalformula (a5-r-1) is preferable.

Specific examples of the substituent which R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹²may have include an alkyl group, a halogen atom, a halogenated alkylgroup, a carbonyl group, a cyano group, an amino group, an aryl groupand groups represented by formulas (ca-r-1) to (ca-r-7) shown below.

In the formulas, R′²⁰¹ each independently represents a hydrogen atom, acyclic group which may have a substituent, a chain-like alkyl groupwhich may have a substituent or a chain-like alkenyl group which mayhave a substituent.

As the cyclic group which may have a substituent, the chain-like alkylgroup which may have a substituent and the chain-like alkenyl groupwhich may have a substituent for R′²⁰¹, the same groups as thosedescribed above for R¹⁰¹ can be mentioned. As the cyclic group which mayhave a substituent and chain-like alkyl group which may have asubstituent, the same groups as those described above for the grouprepresented by the aforementioned formula (a1-r-2) can be alsomentioned.

When R²⁰¹ to R²⁰³, R²⁰⁶ and R²⁰⁷, and R²¹¹ and R²¹² are mutually bondedto form a ring with the sulfur atom, these groups may be mutually bondedvia a hetero atom such as a sulfur atom, an oxygen atom or a nitrogenatom, or a functional group such as a carbonyl group, —SO—, —SO₂—,—SO₃—, —COO—, —CONH— or —N(R_(N))— (wherein R_(N) represents an alkylgroup of 1 to 5 carbon atoms).

As the ring to be formed, the ring containing the sulfur atom in theskeleton thereof is preferably a 3 to 10-membered ring, and mostpreferably a 5 to 7-membered ring.

Examples of the ring to be formed include a thiophene ring, a thiazolering, a benzothiophene ring, a thianthrene ring, a benzothiophene ring,a dibenzothiophene ring, a 9H-thioxanthene ring, a thioxanthone ring, athianthrene ring, a phenoxathiin ring, a tetrahydrothiophenium ring anda tetrahydrothiopyranium ring.

In the formula (ca-4), x represents 1 or 2.

W²⁰¹ represents a linking group having a valency of (x+1), that is, adivalent or trivalent linking group.

As the divalent linking group for W²⁰¹, a divalent hydrocarbon groupwhich may have a substituent is preferable, and as examples thereof, thesame hydrocarbon groups as those described above for Ya²¹ in the generalformula (a2) can be mentioned. The divalent linking group for W²⁰¹ maybe linear, branched or cyclic, and cyclic is more preferable. Amongthese, an arylene group having two carbonyl groups, each bonded to theterminal thereof is preferable. As the arylene group, a phenylene groupand a naphthylene group can be mentioned. Of these, a phenylene group isparticularly desirable.

As the trivalent linking group for W²⁰¹, a group in which one hydrogenatom has been removed from the aforementioned divalent linking group anda group in which the divalent linking group has been bonded to anotherdivalent linking group can be mentioned. The trivalent linking group forW²⁰¹ is preferably an arylene group combined with three carbonyl groups.

Specific examples of preferable cations represented by formula (ca-1)include cations represented by formulas (ca-1-1) to (ca-1-63) shownbelow.

In the formulas, g1, g2 and g3 represent recurring numbers, wherein g1is an integer of 1 to 5, g2 is an integer of 0 to 20, and g3 is aninteger of 0 to 20.

In the formulas, R″²⁰¹ represents a hydrogen atom or a substituent, andas the substituent, the same groups as those described above forsubstituting the R²⁰¹ to R²⁰⁷ and R²¹⁰ to R²¹² can be mentioned.

Specific examples of preferable cations represented by formula (ca-3)include cations represented by formulas (ca-3-1) to (ca-3-6) shownbelow.

Specific examples of preferable cations represented by formula (ca-4)include cations represented by formulas (ca-4-1) and (ca-4-2) shownbelow.

As the component (B), one type of acid generator may be used, or two ormore types may be used in combination.

In the resist composition, the amount of the component (B), relative to100 parts by weight of the component (A) is preferably from 0.5 to 60parts by weight, more preferably from 1 to 50 parts by weight, and stillmore preferably from 1 to 40 parts by weight. When the amount of thecomponent (B) is within the above-mentioned range, formation of a resistpattern can be satisfactorily performed. Further, by virtue of theabove-mentioned range, when each of the components is dissolved in anorganic solvent, a uniform solution can be obtained and the storagestability becomes satisfactory.

<Other Optional Components>

[Component (D)]

Moreover, the resist composition of the present invention may include anacid diffusion control agent component (hereafter, frequently referredto as “component (D)”), in addition to the component (A), or in additionto the component (A) and the component (B).

The component (D) functions as an acid diffusion control agent, i.e., aquencher which traps the acid generated from the component (B) and thelike upon exposure.

In the present invention, the component (D) may be a photodecomposablebase (D1) (hereafter, referred to as “component (D1)”) which isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion, or a nitrogen-containing organic compound (D2)(hereafter, referred to as “component (D2)”) which does not fall underthe definition of component (D1).

(Component (D1))

When a resist pattern is formed using a resist composition containingthe component (D1), the contrast between exposed portions and unexposedportions is improved.

The component (D1) is not particularly limited, as long as it isdecomposed upon exposure and then loses the ability of controlling ofacid diffusion. As the component (D1), at least one compound selectedfrom the group consisting of a compound represented by general formula(d1-1) shown below (hereafter, referred to as “component (d1-1)”), acompound represented by general formula (d1-2) shown below (hereafter,referred to as “component (d1-2)”) and a compound represented by generalformula (d1-3) shown below (hereafter, referred to as “component(d1-3)”) is preferably used.

At exposed portions, the components (d1) to (d1-3) are decomposed andthen lose the ability of controlling of acid diffusion (i.e., basicity),and therefore the components (d1-1) to (d1-3) cannot function as aquencher, whereas at unexposed portions, the components (d1-1) to (d1-3)functions as a quencher.

In the formulas, Rd¹ to Rd⁴ represent a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, provided that,the carbon atom adjacent to the sulfur atom within the Rd² in theformula (d1-2) has no fluorine atom bonded thereto; Yd¹ represents asingle bond or a divalent linking group; and M^(m+) each independentlyrepresents a cation having a valency of m.

{Component (d1-1)}

Anion Moiety

In formula (d1-1), Rd¹ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹.

Among these, as the group for Rd¹, an aromatic hydrocarbon group whichmay have a substituent, an aliphatic cyclic group which may have asubstituent and a chain-like hydrocarbon group which may have asubstituent are preferable. As the substituents which these groups mayhave, a fluorine atom or a fluorinated alkyl group is preferable.

The aromatic hydrocarbon group is preferably a phenyl group or anaphthyl group.

Examples of the aliphatic cyclic group include groups in which one ormore hydrogen atoms have been removed from a polycycloalkane such asadamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane.

As the chain-like hydrocarbon group, a chain-like alkyl group ispreferable. The chain-like alkyl group preferably has 1 to 10 carbonatoms, and specific examples thereof include a linear alkyl group suchas a methyl group, an ethyl group, a propyl group, a butyl group, apentyl group, a hexyl group, a heptyl group, an octyl group, a nonyl ora decyl group, and a branched alkyl group such as a 1-methylethyl group,a 1-methylpropyl group, a 2-methylpropyl group, a 1-methylbutyl group, a2-methylbutyl group, a 3-methylbutyl group, a 1-ethylbutyl group, a2-ethylbutyl group, a 1-methylpentyl group, a 2-methylpentyl group, a3-methylpentyl group or a 4-methylpentyl group.

As the chain-like alkyl group, a fluorinated alkyl group containing afluorine atom or a fluorinated alkyl group as a substituent ispreferable. The fluorinated alkyl group containing a fluorine atom or afluorinated alkyl group as a substituent preferably has 1 to 11 carbonatoms, more preferably 1 to 8, and still more preferably 1 to 4. Thefluorinated alkyl group may contain an atom other than fluorine.Examples of the atom other than fluorine include an oxygen atom, acarbon atom, a hydrogen atom, a sulfur atom and a nitrogen atom.

As Rd¹, a fluorinated alkyl group in which part or all of the hydrogenatoms constituting a linear alkyl group have been substituted withfluorine atom(s) is preferable, and a fluorinated alkyl group in whichall of the hydrogen atoms constituting a linear alkyl group have beensubstituted with fluorine atoms (i.e., a linear pertluoroalkyl group) ismore preferable.

Specific examples of preferable anion moieties for the component (d1-1)are shown below.

Cation Moiety

In formula (d1-1), M^(m+) represents an organic cation having a valencyof m.

The organic cation for M^(m+) is not particularly limited, and examplesthereof include the same cation moieties as those represented by theaforementioned formulas (ca-1) to (ca-4), and cation moietiesrepresented by the aforementioned formulas (ca-1-1) to (ca-1-63) arepreferable.

As the component (d1-1), one type of compound may be used, or two ormore types of compounds may be used in combination.

{(Component (d1-2)}

Anion Moiety

In formula (d1-2), Rd² represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹, provided that, the carbon atomadjacent to the sulfur atom within Rd² group has no fluorine atom bondedthereto (i.e., the carbon atom adjacent to the sulfur atom within Rd²group does not substituted with a fluorine atom). As a result, the anionof the component (d1-2) becomes an appropriately weak acid anion,thereby improving the quenching ability of the component (D).

As Rd², an aliphatic cyclic group which may have a substituent ispreferable, and a group in which one or more hydrogen atoms have beenremoved from adamantane, norbornane, isobornane, tricyclodecane,tetracyclododecane or camphor (which may have a substituent) is morepreferable.

The hydrocarbon group for Rd² may have a substituent. As thesubstituent, the same groups as those described above for substitutingthe hydrocarbon group (e.g., aromatic hydrocarbon group, aliphatichydrocarbon group) for Rd¹ in the formula (d1-1) can be mentioned.

Specific examples of preferable anion moieties for the component (d1-2)are shown below.

Cation Moiety

In formula (d1-2), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-2), one type of compound may be used, or two ormore types of compounds may be used in combination.

{(Component (d1-3)}

Anion Moiety

In formula (d1-3), Rd³ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹, and a cyclic group containing afluorine atom, a chain-like alkyl group or a chain-like alkenyl group ispreferable. Among these, a fluorinated alkyl group is preferable, andmore preferably the same fluorinated alkyl groups as those describedabove for Rd¹.

In formula (d1-3), Rd⁴ represents a cyclic group which may have asubstituent, a chain-like alkyl group which may have a substituent or achain-like alkenyl group which may have a substituent, and is the samegroups as those defined above for R¹⁰¹. Among these, an alkyl groupwhich may have substituent, an alkylene group which may have substituentor a cyclic group which may have substituent is preferable.

The alkyl group for Rd⁴ is preferably a linear or branched alkyl groupof 1 to 5 carbon atoms, and specific examples include a methyl group, anethyl group, a propyl group, an isopropyl group, an n-butyl group, anisobutyl group, a tert-butyl group, a pentyl group, an isopentyl group,and a neopentyl group. Part of the hydrogen atoms within the alkyl groupfor Rd⁴ may be substituted with a hydroxy group, a cyano group or thelike.

As the alkenyl group for Rd⁴, the same groups as those described abovefor R¹⁰¹ can be mentioned, and a vinyl group, a propenyl group (an allylgroup), a 1-methylpropenyl group and a 2-methylpropenyl group arepreferable. These groups may have an alkyl group of 1 to 5 carbon atomsor a halogenated alkyl group of 1 to 5 carbon atoms as a substituent.

As the cyclic group for Rd⁴, the same groups as those described abovefor R¹⁰¹ can be mentioned. Among these, as the cyclic group, analicyclic group (e.g., a group in which one or more hydrogen atoms havebeen removed from a cycloalkane such as cyclopentane, cyclohexane,adamantane, norbornane, isobornane, tricyclodecane ortetracyclododecane) or an aromatic group (e.g., a phenyl group or anaphthyl group) is preferable. When Rd⁴ is an alicyclic group, theresist composition can be satisfactorily dissolved in an organicsolvent, thereby improving the lithography properties. Alternatively,when Rd⁴ is an aromatic group, the resist composition exhibits anexcellent photoadsorption efficiency in a lithography process using EUVor the like as the exposure source, thereby resulting in the improvementof the sensitivity and the lithography properties.

In formula (d1-3), Yd¹ represents a single bond or a divalent linkinggroup.

The divalent linking group for Yd¹ is not particularly limited, andexamples thereof include a divalent hydrocarbon group (aliphatichydrocarbon group, or aromatic hydrocarbon group) which may have asubstituent and a divalent linking group containing a hetero atom. Assuch groups, the same divalent linking groups as those described abovefor Ya²¹ in the formula (a2-1) can be mentioned.

As Yd¹, a carbonyl group, an ester bond, an amide bond, an alkylenegroup or a combination of these is preferable. As the alkylene group, alinear or branched alkylene group is more preferable, and a methylenegroup or an ethylene group is still more preferable.

Specific examples of preferable anion moieties for the component (d1-3)are shown below.

Cation Moiety

In formula (d1-3), M^(m+) is an organic cation having a valency of m,and is the same as defined for M^(m+) in the aforementioned formula(d1-1).

As the component (d1-3), one type of compound may be used, or two ormore types of compounds may be used in combination.

As the component (D1), one type of the aforementioned components (d1-1)to (d1-3), or at least two types of the aforementioned components (d1-1)to (d1-3) can be used in combination.

The amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 10 parts byweight, more preferably from 0.5 to 8 parts by weight, and still morepreferably from 1 to 8 parts by weight.

When the amount of the component (D1) is at least as large as the lowerlimit of the above-mentioned range, excellent lithography properties andexcellent resist pattern shape can be obtained. On the other hand, whenthe amount of the component (D1) is no more than the upper limit of theabove-mentioned range, sensitivity can be maintained at a satisfactorylevel, and through-put becomes excellent.

(Production Method of Components (D1))

The production methods of the components (d1-1) and (d1-2) are notparticularly limited, and the components (d1-1) and (d1-2) can beproduced by conventional methods.

The production method of the component (d1-3) is not particularlylimited. For example, in the case where Rd⁴ in formula (d1-3) is a grouphaving an oxygen atom on the terminal thereof which is bonded to Yd¹,the compound (d1-3) represented by general formula (d1-3) can beproduced by reacting a compound (i-1) represented by general formula(i-1) shown below with a compound (i-2) represented by general formula(i2) shown below to obtain a compound (i-3) represented by generalformula (i-3), and reacting the compound (i-3) with a compoundZ⁻(M^(m+))_(1/m) (i-4) having the desired cation M^(m+), therebyobtaining the compound (d1-3).

In the formulas, Rd⁴, Rd³, and M^(m+) are respectively the same asdefined for Rd⁴, Yd¹, Rd³, and M^(m+) in the aforementioned generalformula (d1-3); Rd^(4a) represents a group in which the terminal oxygenatom has been removed from Rd⁴; and Z⁻ represents a counteranion.

Firstly, the compound (i-1) is reacted with the compound (i-2), therebyobtaining the compound (i-3).

In formula (i-1), Rd^(4a) represents a group in which the terminaloxygen atom has been removed from Rd⁴. In formula (i-2), Yd¹ and Rd³ arethe same as defined above.

As the compound (i-1) and the compound (i-2), commercially availablecompounds may be used, or the compounds may be synthesized.

The method for reacting the compound (i-1) with the compound (i-2) toobtain the compound (i-3) is not particularly limited, but can beperformed, for example, by reacting the compound (i-1) with the compound(i-2) in an organic solvent in the presence of an appropriate acidiccatalyst, followed by washing and recovering the reaction mixture.

The acidic catalyst used in the above reaction is not particularlylimited, and examples thereof include toluenesulfonic acid and the like.The amount of the acidic catalyst is preferably 0.05 to 5 moles, per 1mole of the compound (i-2).

As the organic solvent used in the above reaction, any organic solventwhich is capable of dissolving the raw materials, i.e., the compound(i-1) and the compound (i-2) can be used, and specific examples thereofinclude toluene and the like. The amount of the organic solvent ispreferably 0.5 to 100 parts by weight, more preferably 0.5 to 20 partsby weight, relative to the amount of the compound (i-1). As the solvent,one type may be used alone, or two or more types may be used incombination.

In general, the amount of the compound (i-2) used in the above reactionis preferably 0.5 to 5 moles per 1 mole of the compound (i-1), and morepreferably 0.8 to 4 moles per 1 mole of the compound (i-1).

The reaction time depends on the reactivity of the compounds (i-1) and(i-2), the reaction temperature or the like. However, in general, thereaction time is preferably 1 to 80 hours, and more preferably 3 to 60hours.

The reaction temperature in the above reaction is preferably 20 to 200°C., and more preferably 20 to 150° C.

Next, the obtained compound (i-3) is reacted with the compound (i-4),thereby obtaining the compound (d1-3).

In formula (i-4), M^(m+) is the same as defined above, and Z⁻ representsa counteranion. Z⁻ is not particularly limited, and a conventionalcounteranion can be used.

The method for reacting the compound (i-3) with the compound (i-4) toobtain the compound (d1-3) is not particularly limited, but can beperformed, for example, by dissolving the compound (i-3) in an organicsolvent and water in the presence of an appropriate alkali metalhydroxide, followed by addition of the compound (i-4) and stirring.

The alkali metal hydroxide used in the above reaction is notparticularly limited, and examples thereof include sodium hydroxide,potassium hydroxide and the like. The amount of the alkali metalhydroxide is preferably 0.3 to 3 moles, per 1 mole of the compound(i-3).

Examples of the organic solvent used in the above reaction includedichloromethane, chloroform, ethyl acetate and the like. The amount ofthe organic solvent is preferably 0.5 to 100 parts by weight, and morepreferably 0.5 to 20 parts by weight, relative to the amount of thecompound (i-3). As the solvent, one type may be used alone, or two ormore types may be used in combination.

In general, the amount of the compound (i-4) used in the above reactionis preferably 0.5 to 5 moles per 1 mole of the compound (i-3), and morepreferably 0.8 to 4 moles per 1 mole of the compound (i-3).

The reaction time depends on the reactivity of the compounds (i-3) and(i-4), the reaction temperature or the like. However, in general, thereaction time is preferably 1 to 80 hours, and more preferably 3 to 60hours.

The reaction temperature in the above reaction is preferably 20 to 200°C., and more preferably 20 to 150° C.

After the reaction, the compound (d1-3) contained in the reactionmixture may be separated and purified. The separation and purificationcan be conducted by a conventional method. For example, any one ofconcentration, solvent extraction, distillation, crystallization,recrystallization and chromatography can be used alone, or two or moreof these methods may be used in combination.

The structure of the compound (d1-3) obtained in the above-describedmanner can be confirmed by a general organic analysis method such as¹H-nuclear magnetic resonance (NMR) spectrometry, ¹³C-NMR spectrometry,¹⁹F-NMR spectrometry, infrared absorption (IR) spectrometry, massspectrometry (MS), elementary analysis and X-ray diffraction analysis.

The amount of the component (D1) relative to 100 parts by weight of thecomponent (A) is preferably within a range from 0.5 to 10.0 parts byweight, more preferably from 0.5 to 8.0 parts by weight, and still morepreferably from 1.0 to 8.0 parts by weight. When the amount of thecomponent (D1) is at least as large as the lower limit of theabove-mentioned range, excellent lithography properties and excellentresist pattern shape can be obtained. On the other hand, when the amountof the component (D1) is no more than the upper limit of theabove-mentioned range, sensitivity can be maintained at a satisfactorylevel, and through-put becomes excellent.

(Component (D2))

The component (D) may contain a nitrogen-containing organic compound(D2) (hereafter, referred to as component (D2)) which does not fallunder the definition of component (D1).

The component (D2) is not particularly limited, as long as it functionsas an acid diffusion control agent, and does not fall under thedefinition of the component (D1). As the component (D2), any of theconventionally known compounds may be selected for use. Among these, analiphatic amine, particularly a secondary aliphatic amine or tertiaryaliphatic amine is preferable.

An aliphatic amine is an amine having one or more aliphatic groups, andthe aliphatic groups preferably have 1 to 12 carbon atoms.

Examples of these aliphatic amines include amines in which at least onehydrogen atom of ammonia (NH₃) has been substituted with an alkyl groupor hydroxyalkyl group of no more than 12 carbon atoms (i.e., alkylaminesor alkylalcoholamines), and cyclic amines.

Specific examples of alkylamines and alkylalcoholamines includemonoalkylamines such as n-hexylamine, n-heptylamine, n-octylamine,n-nonylamine, and n-decylamine; dialkylamines such as diethylamine,di-n-propylamine, di-n-heptylamine, di-n-octylamine, anddicyclohexylamine; trialkylamines such as trimethylamine, triethylamine,tri-n-propylamine, tri-n-butylamine, tri-n-hexylamine,tri-n-pentylamine, tri-n-heptylamine, tri-n-octylamine,tri-n-nonylamine, tri-n-decylamine, and tri-n-dodecylamine; and alkylalcohol amines such as diethanolamine, triethanolamine,diisopropanolamine, triisopropanolamine, di-n-octanolamine, andtri-n-octanolamine. Among these, trialkylamines of 5 to 10 carbon atomsare preferable, and tri-n-pentylamine and tri-n-octylamine areparticularly desirable.

Examples of the cyclic amine include heterocyclic compounds containing anitrogen atom as a hetero atom. The heterocyclic compound may be amonocyclic compound (aliphatic monocyclic amine), or a polycycliccompound (aliphatic polycyclic amine).

Specific examples of the aliphatic monocyclic amine include piperidine,and piperazine.

The aliphatic polycyclic amine preferably has 6 to 10 carbon atoms, andspecific examples thereof include 1,5-diazabicyclo[4.3.0]-5-nonene,1,8-diazabicyclo[5.4.0]-7-undecene, hexamethylenetetramine, and1,4-diazabicyclo[2.2.2]octane.

Examples of other aliphatic amines includetris(2-methoxymethoxyethyl)amine, tris{2-(2-methoxyethoxy)ethyl}amine,tris{2-(2-methoxyethoxymethoxy)ethyl}amine,tris{2-(1-methoxyethoxy)ethyl}amine, tris{2-(1-ethoxyethoxy)ethyl}amine,tris{2-(1-ethoxypropoxy)ethyl}amine,tris[2-{2-(2-hydroxyethoxy)ethoxy}ethyl]amine and triethanolaminetriacetate, and triethanolamine triacetate is preferable.

Further, as the component (D2), an aromatic amine may be used.

Examples of aromatic amines include aniline, pyridine,4-dimethylaminopyridine, pyrrole, indole, pyrazole, imidazole andderivatives thereof, as well as diphenylamine, triphenylamine,tribenzylamine, 2,6-diisopropylaniline andN-tert-butoxycarbonylpyrrolidine.

As the component (D2), one type of compound may be used alone, or two ormore types may be used in combination.

The component (D2) is typically used in an amount within a range from0.01 to 5.0 parts by weight, relative to 100 parts by weight of thecomponent (A). When the amount of the component (D2) is within theabove-mentioned range, the shape of the resist pattern and the postexposure stability of the latent image formed by the pattern-wiseexposure of the resist layer are improved.

As the component (D), one type of compound may be used, or two or moretypes of compounds may be used in combination.

When the resist composition of the present invention contains thecomponent (D), the amount of the component (D) relative to 100 parts byweight of the component (A) is preferably within a range from 0.1 to 15parts by weight, more preferably from 0.3 to 12 parts by weight, andstill more preferably from 0.5 to 12 parts by weight. When the amount ofthe component (D) is at least as large as the lower limit of theabove-mentioned range, various lithography properties (such asroughness) of the resist composition are improved. Further, a resistpattern having an excellent shape can be obtained. On the other hand,when the amount of the component (D) is no more than the upper limit ofthe above-mentioned range, sensitivity can be maintained at asatisfactory level, and through-put becomes excellent.

[Component (E)]

Furthermore, in the resist composition of the present invention, forpreventing any deterioration in sensitivity, and improving the resistpattern shape and the post exposure stability of the latent image formedby the pattern-wise exposure of the resist layer, at least one compound(E) (hereafter referred to as the component (E)) selected from the groupconsisting of an organic carboxylic acid, or a phosphorus oxo acid orderivative thereof can be added.

Examples of suitable organic carboxylic acids include acetic acid,malonic acid, citric acid, malic acid, succinic acid, benzoic acid, andsalicylic acid.

Examples of phosphorus oxo acids include phosphoric acid, phosphonicacid and phosphinic acid. Among these, phosphonic acid is particularlydesirable.

Examples of phosphorous oxo acid derivatives include esters in which ahydrogen atom within the above-mentioned phosphorous oxo acids issubstituted with a hydrocarbon group. Examples of the hydrocarbon groupinclude an alkyl group of 1 to 5 carbon atoms and an aryl group of 6 to15 carbon atoms.

Examples of phosphoric acid derivatives include phosphoric acid esterssuch as di-n-butyl phosphate and diphenyl phosphate.

Examples of phosphonic acid derivatives include phosphonic acid esterssuch as dimethyl phosphonate, di-n-butyl phosphonate, phenylphosphonate, diphenyl phosphonate and dibenzyl phosphonate.

Examples of phosphinic acid derivatives include phenylphosphinic acidand phosphinic acid esters.

As the component (E), one type may be used alone, or two or more typesmay be used in combination.

The component (E) is typically used in an amount within a range from0.01 to 5.0 parts by weight, relative to 100 parts by weight of thecomponent (A).

[Component (F)]

In the present invention, the resist composition may further include afluorine additive (hereafter, referred to as “component (F)”) forimparting water repellency to the resist film.

As the component (F), for example, a fluorine-containing polymericcompound described in Japanese Unexamined Patent Application, FirstPublication No. 2010-002870, Japanese Unexamined Patent Application,First Publication No. 2010-032994, Japanese Unexamined PatentApplication, First Publication No. 2010-277043, Japanese UnexaminedPatent Application, First Publication No. 2011-13569, and JapaneseUnexamined Patent Application, First Publication No. 2011-128226 can beused.

Specific examples of the component (F) include polymers having astructural unit (f1) represented by general formula (f1-1) shown below.As the polymer, a polymer (homopolymer) consisting of a structural unit(f1) represented by formula (f1-1) shown below; a copolymer of astructural unit (f1) represented by formula (f1-1) shown below and theaforementioned structural unit (a1); and a copolymer of a structuralunit (f1) represented by formula (f1-1) shown below, a structural unitderived from acrylic acid or methacrylic acid and the aforementionedstructural unit (a1) are preferable. As the structural unit (a1) to becopolymerized with a structural unit (f1) represented by formula (f1-1)shown below, a structural unit derived from1-ethyl-1-cyclooctyl(meth)acrylate or a structural unit represented bythe aforementioned formula (a1-r-01) is preferable.

In the formula, R is the same as defined above; Rf¹⁰² and Rf¹⁰³ eachindependently represents a hydrogen atom, a halogen atom, an alkyl groupof 1 to 5 carbon atoms, or a halogenated alkyl group of 1 to 5 carbonatoms, provided that Rf¹⁰² and Rf¹⁰³ may be the same or different; nf¹represents an integer of 1 to 5; and Rf¹⁰¹ represents an organic groupcontaining a fluorine atom.

In formula (f1-1), R bonded to the carbon atom on the α-position is thesame as defined above. As R, a hydrogen atom or a methyl group ispreferable.

In formula (f1-1), examples of the halogen atom for Rf¹⁰² and Rf¹⁰³include a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a fluorine atom is particularly desirable. Examples of thealkyl group of 1 to 5 carbon atoms for Rf¹⁰² and Rf¹⁰³ include the samealkyl group of 1 to 5 carbon atoms as those described above for R, and amethyl group or an ethyl group is preferable. Specific examples of thehalogenated alkyl group of 1 to 5 carbon atoms represented by Rf¹⁰² andRf¹⁰³ include groups in which part or all of the hydrogen atoms of theaforementioned alkyl groups of 1 to 5 carbon atoms have been substitutedwith halogen atoms. Examples of the halogen atom include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom, and a fluorineatom is particularly desirable. Among these, as Rf¹⁰² and Rf¹⁰³, ahydrogen atom, a fluorine atom or an alkyl group of 1 to 5 carbon atomsis preferable, and a hydrogen atom, a fluorine atom, a methyl group oran ethyl group is more preferable.

In formula (f1-1), nf¹ represents an integer of 1 to 5, preferably aninteger of 1 to 3, and more preferably 1 or 2.

In formula (f1-1), Rf¹⁰¹ represents an organic group containing afluorine atom, and is preferably a hydrocarbon group containing afluorine atom.

The hydrocarbon group containing a fluorine atom may be linear, branchedor cyclic, and preferably has 1 to 20 carbon atoms, more preferably 1 to15 carbon atoms, and most preferably 1 to 10 carbon atoms.

It is preferable that the hydrocarbon group having a fluorine atom has25% or more of the hydrogen atoms within the hydrocarbon groupfluorinated, more preferably 50% or more, and most preferably 60% ormore, as the hydrophobicity of the resist film during immersion exposureis enhanced.

Among these, as Rf¹⁰¹, a fluorinated hydrocarbon group of 1 to 5 carbonatoms is preferable, and a trifluoromethyl group, —CH₂—CF₃,—CH₂—CF₂—CF₃, —CH₂—CH₂—CF₃, —CH(CF₃)₂, —CH₂—CH₂—CF₃, and—CH₂—CH₂—CF₂—CF₂—CF₂—CF₃ are most preferable.

The weight average molecular weight (Mw) (the polystyrene equivalentvalue determined by gel permeation chromatography) of the component (F)is preferably 1,000 to 50,000, more preferably 5,000 to 40,000, and mostpreferably 10,000 to 30,000. When the weight average molecular weight isno more than the upper limit of the above-mentioned range, the resistcomposition exhibits a satisfactory solubility in a resist solvent. Onthe other hand, when the weight average molecular weight is at least aslarge as the lower limit of the above-mentioned range, dry etchingresistance and the cross-sectional shape of the resist pattern becomessatisfactory.

Further, the dispersity (Mw/Mn) of the component (F) is preferably 1.0to 5.0, more preferably 1.0 to 3.0, and most preferably 1.2 to 2.5.

As the component (F), one type may be used alone, or two or more typesmay be used in combination.

The component (F) is typically used in an amount within a range from 0.5to 10 parts by weight, relative to 100 parts by weight of the component(A).

[Other Additives]

If desired, other miscible additives can also be added to the resistcomposition of the present invention. Examples of such miscibleadditives include additive resins for improving the performance of theresist film, dissolution inhibitors, plasticizers, stabilizers,colorants, halation prevention agents, and dyes.

[Component (S)]

The resist composition of the present invention can be prepared bydissolving the materials for the resist composition in an organicsolvent (hereafter, frequently referred to as “component (S)”).

The component (S) may be any organic solvent which can dissolve therespective components to give a uniform solution, and one or more kindsof any organic solvent can be appropriately selected from those whichhave been conventionally known as solvents for a chemically amplifiedresist.

Examples thereof include lactones such as γ-butyrolactone; ketones suchas acetone, methyl ethyl ketone (MEK), cyclohexanone, methyl-n-pentylketone, methyl isopentyl ketone, and 2-heptanone; polyhydric alcohols,such as ethylene glycol, diethylene glycol, propylene glycol anddipropylene glycol; compounds having an ester bond, such as ethyleneglycol monoacetate, diethylene glycol monoacetate, propylene glycolmonoacetate, and dipropylene glycol monoacetate; polyhydric alcoholderivatives including compounds having an ether bond, such as amonoalkylether (e.g., monomethylether, monoethylether, monopropyletheror monobutylether) or monophenylether of any of these polyhydricalcohols or compounds having an ester bond (among these, propyleneglycol monomethyl ether acetate (PGMEA) and propylene glycol monomethylether (PGME) are preferable); cyclic ethers such as dioxane; esters suchas methyl lactate, ethyl lactate (EL), methyl acetate, ethyl acetate,butyl acetate, methyl pyruvate, ethyl pyruvate, methylmethoxypropionate, and ethyl ethoxypropionate; aromatic organic solventssuch as anisole, ethylbenzylether, cresylmethylether, diphenylether,dibenzylether, phenetole, butylphenylether, ethylbenzene,diethylbenzene, pentylbenzene, isopropylbenzene, toluene, xylene, cymeneand mesitylene; and dimethylsulfoxide (DMSO).

These solvents can be used individually, or in combination as a mixedsolvent.

Among these, PGMEA, PGME, γ-butyrolactone and EL are preferable.

Further, among the mixed solvents, a mixed solvent obtained by mixingPGMEA with a polar solvent is preferable. The mixing ratio (weightratio) of the mixed solvent can be appropriately determined, taking intoconsideration the compatibility of the PGMEA with the polar solvent, butis preferably in the range of 1:9 to 9:1, more preferably from 2:8 to8:2.

Specifically, when EL or cyclohexanone is mixed as the polar solvent,the PGMEA:EL weight ratio or PGMEA:cyclohexanone weight ratio ispreferably from 1:9 to 9:1, and more preferably from 2:8 to 8:2.Alternatively, when PGME is mixed as the polar solvent, the PGMEA:PGMEis preferably from 1:9 to 9:1, more preferably from 2:8 to 8:2, andstill more preferably 3:7 to 7:3.

Further, as the component (S), a mixed solvent of at least one of PGMEAand EL with γ-butyrolactone is also preferable. The mixing ratio(former:latter) of such a mixed solvent is preferably from 70:30 to95:5.

The amount of the component (S) is not particularly limited, and isappropriately adjusted to a concentration which enables coating of acoating solution to a substrate. In general, the organic solvent is usedin an amount such that the solid content of the resist compositionbecomes within the range from 1 to 20% by weight, and preferably from 2to 15% by weight.

The resist composition of the present invention includes a component(A1) containing a structural unit (a0), and therefore, in the formationof the resist pattern of the resist film using the resist composition,lithography properties are improved. For example, LWR (line widthroughness), EL (exposure latitude) and MEEF (mask error factor) areimproved. Further, the decrease in film thickness (i.e., film shrinkage)after post exposure bake (PEB) or after development can be suppressed,and for example, in a solvent developing process, a negative-tonepattern can be formed with a high residual film ratio.

The structural unit (A) has R¹ (wherein R¹ represents alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group) at the terminal thereof, and has astructure represented by “—O-(a specific lactone-containing cyclicgroup)-C(═O)—O—” between W² and R′. Therefore, it is presumed that theaforementioned effects can be obtained due to structural unit (a0)having a steric bulkiness and high polarity.

The resist composition of the present invention may be used in an alkalideveloping process or in a solvent developing process. For example, whenthe component (A) is a component (A-1), the resist composition may beused in a method of forming a positive-tone resist pattern in an alkalideveloping process, or in a method of forming a negative-tone resistpattern in a solvent developing process.

In particular, the resist composition of the present invention ispreferably used in a method of forming a negative-tone resist pattern ina solvent developing process. When a negative-tone resist pattern isformed in a solvent developing process, exposed portions remains as aresist pattern, the resist composition of the present invention iscapable of suppressing film shrinkage at exposed portions, which is veryuseful.

<<Method of Forming a Resist Pattern>>

The method of forming a resist pattern of the second aspect of thepresent invention includes: forming a resist film on a substrate using aresist composition of the present invention; conducting exposure of theresist film; and developing the resist film to form a resist pattern.

The method for forming a resist pattern according to the presentinvention can be performed, for example, as follows.

Firstly, the resist composition is applied to a substrate using aspinner or the like, and a bake treatment (post applied bake (PAB)) isconducted at a temperature of 80 to 150° C. for 40 to 120 seconds,preferably 60 to 90 seconds, to form a resist film.

Following selective exposure of the thus formed resist film, either byexposure through a mask having a predetermined pattern formed thereon(mask pattern) using an exposure apparatus such as an ArF exposureapparatus, an electron beam lithography apparatus or an EUV exposureapparatus, or by patterning via direct irradiation with an electron beamwithout using a mask pattern, baking treatment (post exposure baking(PEB)) is conducted under temperature conditions of 80 to 150° C. for 40to 120 seconds, and preferably 60 to 90 seconds.

Next, the resist film is subjected to a developing treatment. Thedeveloping treatment is conducted using an alkali developing solution inthe case of an alkali developing process, and a developing solutioncontaining an organic solvent (organic developing solution) in the caseof a solvent developing process.

After the developing treatment, it is preferable to conduct a rinsetreatment. The rinse treatment is preferably conducted using pure waterin the case of an alkali developing process, and a rinse solutioncontaining an organic solvent in the case of a solvent developingprocess.

In the case of a solvent developing process, after the developingtreatment or the rinsing, the developing solution or the rinse liquidremaining on the pattern can be removed by a treatment using asupercritical fluid.

After the developing treatment or the rinse treatment, drying isconducted. If desired, bake treatment (post bake) can be conductedfollowing the developing. In this manner, a resist pattern can beobtained.

The substrate is not specifically limited and a conventionally knownsubstrate can be used. For example, substrates for electroniccomponents, and such substrates having wiring patterns formed thereoncan be used. Specific examples of the material of the substrate includemetals such as silicon wafer, copper, chromium, iron and aluminum; andglass. Suitable materials for the wiring pattern include copper,aluminum, nickel, and gold.

Further, as the substrate, any one of the above-mentioned substratesprovided with an inorganic and/or organic film on the surface thereofmay be used. As the inorganic film, an inorganic anti-reflection film(inorganic BARC) can be used. As the organic film, an organicantireflection film (organic BARC) and an organic film such as alower-layer organic film used in a multilayer resist method can be used.

Here, a “multilayer resist method” is method in which at least one layerof an organic film (lower-layer organic film) and at least one layer ofa resist film (upper resist film) are provided on a substrate, and aresist pattern formed on the upper resist film is used as a mask toconduct patterning of the lower-layer organic film. This method isconsidered as being capable of forming a pattern with a high aspectratio. More specifically, in the multilayer resist method, a desiredthickness can be ensured by the lower-layer organic film, and as aresult, the thickness of the resist film can be reduced, and anextremely fine pattern with a high aspect ratio can be formed.

The multilayer resist method is broadly classified into a method inwhich a double-layer structure consisting of an upper-layer resist filmand a lower-layer organic film is formed (double-layer resist method),and a method in which a multilayer structure having at least threelayers consisting of an upper-layer resist film, a lower-layer organicfilm and at least one intermediate layer (thin metal film or the like)provided between the upper-layer resist film and the lower-layer organicfilm (triple-layer resist method).

The wavelength to be used for exposure is not particularly limited andthe exposure can be conducted using radiations such as ArF excimerlaser, KrF excimer laser, F₂ excimer laser, extreme ultraviolet rays(EUV), vacuum ultraviolet rays (VUV), electron beam (EB), X-rays, andsoft X-rays. The resist composition of the present invention iseffective to KrF excimer laser, ArF excimer laser, EB and EUV, andparticularly effective to ArF excimer laser, EB and EUV.

The exposure of the resist film can be either a general exposure (dryexposure) conducted in air or an inert gas such as nitrogen, orimmersion exposure (immersion lithography).

In immersion lithography, the region between the resist film and thelens at the lowermost point of the exposure apparatus is pre-filled witha solvent (immersion medium) that has a larger refractive index than therefractive index of air, and the exposure (immersion exposure) isconducted in this state.

The immersion medium preferably exhibits a refractive index larger thanthe refractive index of air but smaller than the refractive index of theresist film to be exposed. The refractive index of the immersion mediumis not particularly limited as long at it satisfies the above-mentionedrequirements.

Examples of this immersion medium which exhibits a refractive index thatis larger than the refractive index of air but smaller than therefractive index of the resist film include water, fluorine-based inertliquids, silicon-based solvents and hydrocarbon-based solvents.

Specific examples of the fluorine-based inert liquids include liquidscontaining a fluorine-based compound such as C₃HCl₂F₅, C₄F₉OCH₃,C₄F₉OC₂H₅ or C₅H₃F₇ as the main component, which have a boiling pointwithin a range from 70 to 180° C. and preferably from 80 to 160° C. Afluorine-based inert liquid having a boiling point within theabove-mentioned range is advantageous in that the removal of theimmersion medium after the exposure can be conducted by a simple method.

As a fluorine-based inert liquid, a perfluoroalkyl compound in which allof the hydrogen atoms of the alkyl group are substituted with fluorineatoms is particularly desirable. Examples of these perfluoroalkylcompounds include perfluoroalkylether compounds and perfluoroalkylaminecompounds.

Specifically, one example of a suitable perfluoroalkylether compound isperfluoro(2-butyl-tetrahydrofuran) (boiling point 102° C.), and anexample of a suitable perfluoroalkylamine compound isperfluorotributylamine (boiling point 174° C.).

As the immersion medium, water is preferable in terms of cost, safety,environment and versatility.

As an example of the alkali developing solution used in an alkalideveloping process, a 0.1 to 10% by weight aqueous solution oftetramethylammonium hydroxide (TMAH) can be given.

As the organic solvent contained in the organic developing solution usedin a solvent developing process, any of the conventional organicsolvents can be used which are capable of dissolving the component (A)(prior to exposure). Specific examples of the organic solvent includepolar solvents such as ketone solvents, ester solvents, alcoholsolvents, nitrile solvents, amide solvents and ether solvents, andhydrocarbon solvents.

A ketone solvent is an organic solvent containing C—C(═O)—C within thestructure thereof. An ester solvent is an organic solvent containingC—C(═O)—O—C within the structure thereof. An alcohol solvent is anorganic solvent containing an alcoholic hydroxy group within thestructure thereof, and an “alcoholic hydroxy group” refers to a hydroxygroup bonded to a carbon atom of an aliphatic hydrocarbon group. Anitrile solvent is an organic solvent containing a nitrite group in thestructure thereof. An amide solvent is an organic solvent containing anamide group within the structure thereof. An ether solvent is an organicsolvent containing C—O—C within the structure thereof.

Some organic solvents have a plurality of the functional groups whichcharacterizes the aforementioned solvents within the structure thereof.In such a case, the organic solvent can be classified as any type of thesolvent having the characteristic functional group. For example,diethyleneglycol monomethylether can be classified as either an alcoholsolvent or an ether solvent.

A hydrocarbon solvent consists of a hydrocarbon which may behalogenated, and does not have any substituent other than a halogenatom. Examples of the halogen atom include a fluorine atom, a chlorineatom, a bromine atom and an iodine atom, and a fluorine atom ispreferable.

As the organic solvent contained in the organic developing solution,among these, a polar solvent is preferable, and ketone solvents, estersolvents and nitrile solvents are preferable.

Specific examples of ketone solvents include 1-octanone, 2-octanone,1-nonanone, 2-nonanone, acetone, 4-heptanone, 1-hexanone, 2-hexanone,diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone,methyl ethyl ketone, methyl isobutyl ketone, acetylacetone,acetonylacetone, ionone, diacetonylalcohol, acetylcarbinol,acetophenone, methyl naphthyl ketone, isophorone, propylenecarbonate,γ-butyrolactone and methyl amyl ketone (2-heptanone).

As a ketone solvent, methyl amyl ketone (2-heptanone) is preferable.

Examples of ester solvents include methyl acetate, butyl acetate, ethylacetate, isopropyl acetate, amyl acetate, isoamyl acetate, ethylmethoxyacetate, ethyl ethoxyacetate, propylene glycol monomethyl etheracetate, ethylene glycol monoethyl ether acetate, ethylene glycolmonopropyl ether acetate, ethylene glycol monobutyl ether acetate,ethylene glycol monophenyl ether acetate, diethylene glycol monomethylether acetate, diethylene glycol monopropyl ether acetate, diethyleneglycol monoethyl ether acetate, diethylene glycol monophenyl etheracetate, diethylene glycol monobutyl ether acetate, diethylene glycolmonoethyl ether acetate, 2-methoxybutyl acetate, 3-methoxybutyl acetate,4-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate,3-ethyl-3-methoxybutyl acetate, propylene glycol monomethyl etheracetate, propylene glycol monoethyl ether acetate, propylene glycolmonopropyl ether acetate, 2-ethoxybutyl acetate, 4-ethoxybutyl acetate,4-propoxybutyl acetate, 2-methoxypentyl acetate, 3-methoxypentylacetate, 4-methoxypentyl acetate, 2-methyl-3-methoxypentyl acetate,3-methyl-3-methoxypentyl acetate, 3-methyl-4-methoxypentyl acetate,4-methyl-4-methoxypentyl acetate, propylene glycol diacetate, methylformate, ethyl formate, butyl formate, propyl formate, ethyl lactate,butyl lactate, propyl lactate, ethyl carbonate, propyl carbonate, butylcarbonate, methyl pyruvate, ethyl pyruvate, propyl pyruvate, butylpyruvate, methyl acetoacetate, ethyl acetoacetate, methyl propionate,ethyl propionate, propyl propionate, isopropyl propionate, methyl2-hydroxypropionate, ethyl 2-hydroxypropionate,methyl-3-methoxypropionate, ethyl-3-methoxypropionate,ethyl-3-ethoxypropionate and propyl-3-methoxypropionate.

As an ester solvent, butyl acetate is preferable.

Examples of nitrile solvents include acetonitrile, propionitrile,valeronitrile, butyronitrile and the like.

If desired, the organic developing solution may have a conventionaladditive blended. Examples of the additive include surfactants. Thesurfactant is not particularly limited, and for example, an ionic ornon-ionic fluorine and/or silicon surfactant can be used. As thesurfactant, a non-ionic surfactant is preferable, and a fluorinesurfactant or a silicon surfactant is more preferable.

When a surfactant is added, the amount thereof based on the total amountof the organic developing solution is generally 0.001 to 5% by weight,preferably 0.005 to 2% by weight, and more preferably 0.01 to 0.5% byweight.

The developing treatment can be performed by a conventional developingmethod. Examples thereof include a method in which the substrate isimmersed in the developing solution for a predetermined time (a dipmethod), a method in which the developing solution is cast up on thesurface of the substrate by surface tension and maintained for apredetermined period (a puddle method), a method in which the developingsolution is sprayed onto the surface of the substrate (spray method),and a method in which the developing solution is continuously ejectedfrom a developing solution ejecting nozzle while scanning at a constantrate to apply the developing solution to the substrate while rotatingthe substrate at a constant rate (dynamic dispense method).

As the organic solvent contained in the rinse liquid used in the rinsetreatment after the developing treatment in the case of a solventdeveloping process, any of the aforementioned organic solvents containedin the organic developing solution can be used which hardly dissolvesthe resist pattern. In general, at least one solvent selected from thegroup consisting of hydrocarbon solvents, ketone solvents, estersolvents, alcohol solvents, amide solvents and ether solvents is used.Among these, at least one solvent selected from the group consisting ofhydrocarbon solvents, ketone solvents, ester solvents, alcohol solventsand amide solvents is preferable, more preferably at least one solventselected from the group consisting of alcohol solvents and estersolvents, and an alcohol solvent is particularly desirable.

The alcohol solvent used for the rinse liquid is preferably a monohydricalcohol of 6 to 8 carbon atoms, and the monohydric alcohol may belinear, branched or cyclic. Specific examples thereof include 1-hexanol,1-heptanol, 1-octanol, 2-hexanol, 2-heptanol, 2-octanol, 3-hexanol,3-heptanol, 3-octanol, 4-octanol and benzyl alcohol. Among these,1-hexanol, 2-heptanol and 2-hexanol are preferable, and 1 hexanol and2-hexanol are more preferable.

These organic solvents can be used individually, or at least 2 solventsmay be mixed together. Further, an organic solvent other than theaforementioned examples or water may be mixed together. However, inconsideration of the development characteristics, the amount of waterwithin the rinse liquid, based on the total amount of the rinse liquidis preferably 30% by weight or less, more preferably 10% by weight orless, still more preferably 5% by weight or less, and most preferably 3%by weight or less.

If desired, the rinse solution may have a conventional additive blended.Examples of the additive include surfactants. As the surfactant, thesame surfactants as those described above can be mentioned, and anon-ionic surfactant is preferable, and a fluorine surfactant or asilicon surfactant is more preferable.

When a surfactant is added, the amount thereof based on the total amountof the rinse liquid is generally 0.001 to 5% by weight, preferably 0.005to 2% by weight, and more preferably 0.01 to 0.5% by weight.

The rinse treatment using a rinse liquid (washing treatment) can beconducted by a conventional rinse method. Examples of the rinse methodinclude a method in which the rinse liquid is continuously applied tothe substrate while rotating it at a constant rate (rotational coatingmethod), a method in which the substrate is immersed in the rinse liquidfor a predetermined time (dip method), and a method in which the rinseliquid is sprayed onto the surface of the substrate (spray method).

<<Polymeric Compound>>

The polymeric compound according to the third aspect of the presentinvention has a structural unit (a0) represented by general formula (a0)shown below.

The explanation of the polymeric compound of the present invention isthe same as the explanation of the component (A1) of the resistcomposition of the present invention described above.

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; R¹ represents a lactone-containing cyclic group, an—SO₂— containing cyclic group or a carbonate-containing cyclic group;and W² represents a group which is formed by polymerization reaction ofa group containing a polymerizable group.

<<Compound According to Fourth Aspect>>

The compound according to a fourth aspect of the present invention is acompound represented by general formula (I) shown below (hereafter, thiscompound is referred to as “compound (I)”).

The compound (I) is useful as a raw material for the polymeric compoundof the present invention. By using the compound (I) as a monomer, thepolymeric compound containing the structural unit represented by thegeneral formula (a0) can be obtained.

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; R¹ represents a lactone-containing cyclic group, an—SO₂— containing cyclic group or a carbonate-containing cyclic group;and R² represents a group containing a polymerizable group.

A″ and R¹ in the formula (I) are respectively the same as defined abovefor A″ and R¹ in the general formula (a0).

The “group containing a polymerizable group” for R² is the same groupsas those described above for the “group containing a polymerizablegroup” in the explanation of W² in the general formula (a0).

<Production Method of Compound (I)>

The method for producing the compound (I) is not particularly limited,and the compound (I) can be produced by a conventional method.

For example, compound (I) can be produced by a producing methodcontaining: a first step in which a compound (01) represented by generalformula (01) shown below and a compound (02) represented by generalformula (02) shown below are dissolved in solvent and react in thepresence of base to obtain a compound (03) represented by generalformula (03) shown below;

a second step in which the obtained compound (03) is subjected to anoxydation-cyclization reaction to obtain compound (II) represented bygeneral formula (II) shown below; and

a third step in which the R² group (i.e., a group containing apolymerizable group) is introduced into the hydroxy group of theobtained compound (II).

As the compounds (01) and (02), commercially available compounds may beused, or the compounds may be synthesized by a conventional method.

The solvent used in the first step may be any solvent which can dissolvethe compounds (01) and (02) and which cannot react with these compounds,and for examples thereof include dichloromethane, di chloroethane,chloroform, tetrahydrofuran, N,N-dimethylformamide, acetonitrile andpropionitrile.

Examples of the base include inorganic bases such as sodium hydride,K₂CO₃ and Cs₂CO₃, and organic bases such as triethylamine,N,N-dimethylaminopyridine and pyridine.

The oxydation-cyclization reaction in the second step can be conductedby a conventional method in which an oxidizing reagent such as performicacid, peracetic acid and m-chloroperoxybenzoic acid is used.

In the third step, the R² can be introduced by a conventional method bywhich a group containing a polymerizable group is introduced into ahydroxy group of an alcohol. The third step may be one step or multisteps.

For example, when a group containing a carbonyl group (e.g.,(meth)acryloyloxy group) is introduced as a R² group into the terminalof the oxygen-side of the hydroxy group of the compound (II), byreacting the compound (II) and R²—X (wherein X represents a halogen atomsuch as chlorine atom or a hydroxy group), the objective compound can beobtained.

After the reaction, the compound within the reaction mixture may beseparated and purified. The separation and purification can be conductedby a conventional method. For example, any one of concentration, solventextraction, distillation, crystallization, recrystallization andchromatography can be used alone, or two or more of these methods may beused in combination.

The structure of the compound obtained in the above-described manner canbe confirmed by a general organic analysis method such as ¹H-nuclearmagnetic resonance (NMR) spectrometry, ¹³C-NMR spectrometry, ¹⁹F-NMRspectrometry, infrared absorption (IR) spectrometry, mass spectrometry(MS), elementary analysis and X-ray diffraction analysis.

<<Compound According to Fifth Aspect>>

The compound according to a fifth aspect of the present invention is acompound represented by general formula (II) shown below (hereafter,this compound is referred to as “compound (II)”).

In the formula, A″ represents an oxygen atom, a sulfur atom or analkylene group of 1 to 5 carbon atoms which may contain an oxygen atomor a sulfur atom; and R′ represents a lactone-containing cyclic group,an —SO₂— containing cyclic group or a carbonate-containing cyclic group.

A″ and R¹ in the formula (II) are respectively the same as defined abovefor A″ and R¹ in the general formula (a0).

The compound (II) is useful as a raw material (intermediate) for thecompound (I). As described above, by introducing the R² group (i.e., agroup containing a polymerizable group) into the hydroxy group ofcompound (II), the compound (I) can be obtained.

EXAMPLES

As follows is a description of examples of the present invention,although the scope of the present invention is by no way limited bythese examples.

Hereafter, a compound represented by a chemical formula I is designatedas compound 1, and the same applies for compounds represented by otherchemical formulae.

In the NMR analysis, the internal standard for ¹H-NMR and ¹³C-NMR wastetramethylsilane (TMS).

Synthesis Example 1 Synthesis of Compound H-1

46.8 g of alcohol 1 and 40.3 g of N,N-dimethylaminopyridine weredissolved in 490 g of dichloromethane and then cooled in ice. Adichloromethane solution containing 49.3 g of HIMIC anhydride was addedto the obtained solution in a dropwise manner. Thereafter, the solutionwas heated to 25° C. and reaction was conducted for 12 hours, followedby cooling in ice, and then 490 g of diluted hydrochloric acid was addedthereto to stop the reaction. Subsequently, the reaction solution waswashed with pure water three times, and 4900 g of hexane was addedthereto, thereby obtaining 61 g of compound H-1.

The obtained compound was analyzed by NMR, and the structure thereof wasidentified by the following results.

¹H-NMR (400 MHz, DMSO-d6): δ(ppm)=11.97 (1H, OH), 6.19-6.24 (1H, C═CH),6.04-6.06 (1H, C═CH), 5.36-5.41 (1H, CH), 4.56-4.63 (3H, CH), 3.22-3.37(2H, CH), 3.06 (2H, CH), 2.65-2.70 (1H, CH), 1.99-2.11 (2H, CH),1.28-1.36 (2H, CH₂).

Synthesis Example 2 Synthesis of Compound H-2

6.4 g of the compound H-1 was dissolved in 15.9 g of 88% formic acid,and the temperature was elevated to 45° C. 2.5 g of 35% hydrogenperoxide solution was added to the obtained solution in a dropwisemanner over 1 hour. The reaction was conducted at 45° C. for 12 hours,followed by cooling in ice, and then 1.5 g of sodium hydrogen sulfitewas added thereto to quench the excess peroxide. Then, 6.5 g of purewater and 3.5 g of sodium chloride were added to the obtained solution,and extraction was conducted using 34 g of dichloromethane five times.The dichloromethane phase were combined, and washed with sodiumhydrocarbonate aqueous solution, and then pure water, and the solventwas distilled off under reduced pressure, thereby obtaining 2.2 g ofcompound H-2.

The obtained compound was analyzed by NMR, and the structure thereof wasidentified by the following results.

¹H-NMR (400 MHz, DMSO-d6): δ(ppm)=5.43-5.46 (1H, CH), 5.27-5.29 (1H,CH), 4.77 (1H, CH), 4.52-4.66 (2H, CH), 4.35-4.37 (1H, CH), 4.04-4.08(1H, CH), 3.15-3.24 (2H, CH), 2.69-2.79 (2H, CH), 2.45-2.50 (1H, CH),2.08-2.11 (2H, CH), 1.99 (1H, CH₂), 1.55 (1H, CH₂).

Synthesis Example 3 Synthesis of Compound L-1

14 g of compound H-2 was dissolved in 140 g of dichloromethane andcooled in ice. 5.3 g of trimethylamine was added to the obtainedsolution in a dropwise manner, and then a dichloromethane solutioncontaining 4.6 g of methacrylic acid chloride was slowly added theretoin a dropwise manner. The reaction was continuously conducted for 3hours, and then pure water was added to the reaction solution to stopthe reaction. A liquid separation was conducted, and dichloromethanephase was washed with diluted hydrochloric acid, and then pure waterthree times. The obtained solution was added to 1400 g of diisopropylether in a dropwise manner, thereby obtaining 13 g of compound L-1.

The obtained compound was analyzed by NMR, and the structure thereof wasidentified by the following results.

¹H-NMR (400 MHz, DMSO-d6): δ(ppm)=6.07 (1H, C═CH), 5.73 (1H, C═CH), 5.41(1H, CH), 5.17 (1H, CH), 4.80 (1H, CH), 4.52-4.68 (3H, CH), 3.28-3.40(2H, CH), 2.85-2.91 (1H, CH), 2.69-2.73 (2H, CH), 2.08-2.14 (2H, CH₂),1.95 (1H, CH₂), 1.89 (3H, CH₃), 1.73 (1H, CH₂).

Synthesis Example 4 Synthesis of Compound L-2

The same procedure as in Synthesis Example 3 was performed, except thatthe 4.6 g of methacrylic acid chloride was changed to equimolar amountsof CH₂═C(CH₃)C(═O)OCH₂C(═O)Cl, thereby obtaining 12 g of compound L-2.

The obtained compound was analyzed by NMR, and the structure thereof wasidentified by the following results.

¹H-NMR (400 MHz, DMSO-d6): δ(ppm)=6.13 (1H, C═CH), 5.81 (1H, C═CH), 5.45(1H, CH), 5.17 (1H, CH), 4.78-4.81 (3H, CH+CH₂O), 4.52-4.68 (3H, CH),3.28-3.40 (2H, CH), 2.85-2.91 (1H, CH), 2.69-2.73 (2H, CH), 2.08-2.14(2H, CH₂), 1.95 (1H, CH₂), 1.89 (3H, CH₃), 1.73 (1H, CH₂).

Synthesis Example 5 Synthesis of Compounds L-3 to L6, Compound (3)

The same procedure for producing compound L-1 or L-2 was performed,except that HIMIC anhydride or alcohol 1 was changed to a correspondingcarboxylic anhydride or a corresponding alcohol, thereby obtainingcompounds L-3 to L-6 and compound (3).

Synthesis Example 6 Synthesis of Polymer-2

7.6 g of γ-butyrolactone (GBL) was added to a flask equipped with athermometer, a reflux tube, a stirrer and a N₂ inlet tube under anitrogen atmosphere, and the internal temperature was raised to 85° C.while stirring.

8.1 g (17.6 mmol) of compound L-2 and 4.5 g (22.9 mmol) of PcpMA weredissolved in 33 g of γ-butyrolactone (GBL). Then, 0.56 g of V-601 as apolymerization initiator was added and dissolved in the obtainedsolution.

The mixed solution was added to the flask in a dropwise manner at aconstant rate over 4 hours, and then heated while stirring for 1 hour,and the reacting solution was cooled at room temperature.

The obtained reaction polymer solution was added to an excess amount ofa methanol-water mixed solution in a dropwise manner, and an operationto deposit a polymer was conducted. Thereafter, the precipitated whitepowder was separated by filtration, followed by washing with amethanol-water mixed solution and drying under reduced pressure, therebyobtaining 6.2 g of a polymeric compound (Polymer-2) as an objectivecompound.

With respect to the polymeric compound, the weight average molecularweight (Mw) and the dispersity (PDI (Mw/Mn)) were determined by thepolystyrene equivalent value as measured by gel permeationchromatography (GPC). As a result, it was found that the weight averagemolecular weight was 7,600, and the dispersity was 1.71. Further, as aresult of an analysis by ¹³C-NMR, it was found that the copolymercompositional ratio (ratio (molar ratio) of the respective structuralunits within the structural formula) was L-2/PcpMA=49/51.

Synthesis Examples 7 to 20 Synthesis of Polymer-1, 3 to 7, R1 to R6, F1and F2

Polymer-1, 3 to 7 and 11 to 18 were synthesized by the same procedure asin Synthesis Example 6, except that the monomers used and the amountthereof were changed. With respect to each polymeric compound, Mw, PDTand compositional ratio (ratio (molar ratio) of the respectivestructural units within the structural formula) were determined as inthe same manner described above.

The structural formulas of monomers used in the synthesis of Polymer-1to 7, R¹ to R6, F1 and F2, Mw, PDI and compositional ratio arecollectively shown below. With respect to Mw, the term “K” means“×10^(3”), and for example, 7.5K means that Mw is 7500.

Comparative Example 1, Example 1, Comparative Example 2, Examples 2 to 4

The components shown in Table 1 were mixed together and dissolved toobtain resist compositions.

TABLE 1 Compo- Compo- Compo- Compo- nent nent nent nent Component (A)(B) (D) (F) (S) Comparative (A)-R1 (B)-1 (D)-1 (F)-1 (S)-1 (S)-2 Example1 [100] [10] [4.2] [3.3] [10] [3000] Example 1 (A)-1 (B)-1 (D)-1 (F)-1(S)-1 (S)-2 [100] [10] [4.2] [3.3] [10] [3000] Comparative (A)-R2 (B)-1(D)-1 (F)-1 (S)-1 (S)-2 Example 2 [100] [10] [4.2] [3.3] [10] [3000]Example 2 (A)-2 (B)-1 (D)-1 (F)-1 (S)-1 (S)-2 [100] [10] [4.2] [3.3][10] [3000] Example 3 (A)-3 (B)-1 (D)-1 (F)-1 (S)-1 (S)-2 [100] [10][4.2] [3.3] [10] [3000] Example 4 (A)-4 (B)-1 (D)-1 (F)-1 (S)-1 (S)-2[100] [10] [4.2] [3.3] [10] [3000] In Table 1, the values in brackets [] indicate the amount (in terms of parts by weight) of the componentadded. The reference characters indicate the following. (A)-1 to (A)-4:the aforementioned Polymer-1 to Polymer-4, respectively (A)-R1 and(A)-R2: the aforementioned Polymer-R1 and Polymer-R2, respectively(B)-1: a compound represented by structural formula (B)-1 shown below(D)-1: a compound represented by structural formula (D)-1 shown below(F)-1: the aforementioned Polymer-F1 (S)-1: γ-butyrolactone (S)-2: amixed solvent of PGMEA/PGME/cyclohexanone = 45/30/25 (weight ratio)[Chemical Formula 69]

Using the obtained resist compositions, the following evaluations wereconducted.

[Formation of Resist Pattern 1]

An organic anti-reflection film composition (product name: ARC29,manufactured by Brewer Science Ltd.) was applied to a 12-inch siliconwafer using a spinner, and the composition was then baked and dried on ahotplate at 205° C. for 60 seconds, thereby forming an organicanti-reflection film having a film thickness of 89 nm.

Then, the resist compositions was applied onto the anti-reflection filmusing a spinner, and was then prebaked (PAB) on a hotplate at atemperature indicated in Table 2 for 60 seconds and dried, therebyforming a resist film having a film thickness of 80 nm.

Subsequently, the resist film was selectively irradiated with an ArFexcimer laser (193 nm) through a photomask (6% halftone), using animmersion lithography ArF exposure apparatus NSR-560913 (manufactured byNikon Corporation; NA (numerical aperture)=1.07; Dipole 0.97/0.78w/Polano; immersion medium: water). Further, PEB treatment was conductedat a temperature indicated in Table 2 for 60 seconds.

Next, an alkali development was conducted for 10 seconds at 23° C. in a2.38% by weight aqueous solution of tetramethylammonium hydroxide (TMAH)(product name: NMD-3; manufactured by Tokyo Ohka Kogyo Co., Ltd.). Then,the resist was washed for 30 seconds with pure water, followed by dryingby shaking.

As a result, in each of the examples, a line and space pattern (LSpattern) having a line width of 50 nm and a pitch of 100 nm was formed.

[Evaluation of Exposure Latitude (EL)]

The exposure dose with which an LS pattern was formed in theaforementioned [Formation of resist pattern 1] and having a dimension ofthe target dimension ±5% (i.e., 47.5 nm to 52.5 nm) was determined, andthe EL (unit: %) was determined by the following formula. The resultsare indicated “5% EL” in Table 2. The larger the value of the “EL”, thesmaller the change in the pattern size by the variation of the exposuredose.EL (%)=(|E1−E2|/Eop)×100

In the formula, E1 represents the exposure dose (mJ/cm²) for forming aLS pattern having a line width of 47.5 nm, E2 represents the exposuredose (mJ/cm²) for forming a LS pattern having a line width of 52.5 nm,and Eop represents the optimum exposure dose with which the LS patternhaving a line width of 50 nm and a pitch of 100 nm was formed. Eop wasdetermined by a conventional method.

[Evaluation of Line Width Roughness (LWR)]

With respect to the LS pattern formed in the aforementioned [Formationof resist pattern 1], the space width at 400 points in the lengthwisedirection of the space were measured using a measuring scanning electronmicroscope (SEM) (product name: S-9380, manufactured by HitachiHigh-Technologies Corporation; acceleration voltage: 300V). From theresults, the value of 3 times the standard deviation s (i.e., 3s) wasdetermined, and the average of the 3s values at 400 points wascalculated as a yardstick of LWR. The results are shown in Table 2. Thesmaller this 3s value is, the lower the level of roughness of the linewidth, indicating that a LS pattern with a uniform width was obtained.

[Evaluation of Mask Error Factor (MEEF)]

In the same manner as in the formation of LS pattern formed in theaforementioned [Formation of resist pattern 1], with the same exposuredose, LS patterns with a pitch of 100 nm were formed using a maskpattern targeting a line pattern size of 45 to 54 nm (10 target sizes atintervals of 1 nm). The value of the mask error factor (MEEF) wasdetermined as the gradient of a graph obtained by plotting the targetsize (nm) on the horizontal axis, and the size (nm) of the formed linepatterns on the vertical axis. The results are shown in Table 2. A MEEFvalue (gradient of the plotted line) closer to 1 indicates that a resistpattern faithful to the mask pattern was formed.

TABLE 2 PAB/PEB (° C.) 5% EL (%) LWR (nm) MEEF Comparative 120/100 6.96.00 3.25 Example 1 Example 1 120/100 7.8 5.67 2.91 Comparative 100/856.9 6.00 3.18 Example 2 Example 2 100/90 7.8 5.22 2.65 Example 3 100/908.8 4.95 2.61 Example 4 100/90 8.3 5.31 2.87

As shown in the aforementioned results, in the resist composition ofExample 1, 5% EL, LWR and MEEF were improved, as compared to ComparativeExample 1 which had the same composition except for the “structural unitcontaining a lactone-containing cyclic group” contained in the component(A).

Likewise, in the resist compositions of Examples 2 to 4, lithographyproperties such as 5% EL, LWR and MEEF were improved, as compared toComparative Example 2 which had the same composition except for the“structural unit containing a lactone-containing cyclic group” containedin the component (A).

Comparative Examples 3 to 6, Examples 5 to 9, Comparative Example 7,Example 10

The components shown in Table 3 were mixed together and dissolved toobtain resist compositions.

TABLE 3 Compo- Compo- Compo- nent Component nent nent Component (A) (B)(D) (F) (S) Comparative (A)-R2 (B)-2 (B)-3 (D)-2 (F)-2 (S)-1 (S)-3Example 3 [100]  [6] [1] [3.5] [4.0] [100] [3000] Comparative (A)-R3(B)-2 (B)-3 (D)-2 (F)-2 (S)-1 (S)-3 Example 4 [100]  [6] [1] [3.5] [4.0][100] [3000] Comparative (A)-R4 (B)-2 (B)-3 (D)-2 (F)-2 (S)-1 (S)-3Example 5 [100]  [6] [1] [3.5] [4.0] [100] [3000] Comparative (A)-R5(B)-2 (B)-3 (D)-2 (F)-2 (S)-1 (S)-3 Example 6 [100]  [6] [1] [3.5] [4.0][100] [3000] Example 5 (A)-2 (B)-2 (13)-3 (D)-2 (F)-2 (S)-1 (S)-3 [100] [6] [1] [3.5] [4.0] [100] [3000] Example 6 (A)-3 (B)-2 (B)-3 (D)-2(F)-2 (S)-1 (S)-3 [100]  [6] [1] [3.5] [4.0] [100] [3000] Example 7(A)-4 (B)-2 (B)-3 (D)-2 (F)-2 (S)-1 (S)-3 [100]  [6] [1] [3.5] [4.0][100] [3000] Example 8 (A)-5 (B)-2 (B)-3 (D)-2 (F)-2 (S)-1 (S)-3 [100] [6] [1] [3.5] [4.0] [100] [3000] Example 9 (A)-6 (B)-2 (B)-3 (D)-2(F)-2 (S)-1 (S)-3 [100]  [6] [1] [3.5] [4.0] [100] [3000] Comparative(A)-R6 (B)-1 — (D)-2 (F)-2 (S)-1 (S)-3 Example 7 [100] [10] [3.5] [4.0][100] [3000] Example 10 (A)-7 (B)-1 — (D)-2 (F)-2 (S)-1 (S)-3 [100] [10][3.5] [4.0] [100] [3000] In Table 3, the values in brackets [ ] indicatethe amount (in terms of parts by weight) of the component added. Thereference characters indicate the following. (A)-2 to (A)-7: theaforementioned Polymer-2 to Polymer-7, respectively (A)-R2 to (A)-R6:the aforementioned Polymer-R2 to Polymer-R6, respectively (B)-1: acompound represented by the aforementioned structural formula (B)-1(B)-2 and (B)-3: compounds represented by structural formulas (B)-2 and(B)-3 shown below, respectively (D)-2: a compound represented bystructural formula (D)-2 shown below (F)-2: the aforementionedPolymer-F2 (S)-1: γ-butyrolactone (S)-3: a mixed solvent ofPGMEA/cyclohexanone = 90/10 (weight ratio) [Chemical Formula 70]

Using the obtained resist compositions, the following evaluations andmeasurements were conducted.

[Formation of Resist Pattern 2]

An organic anti-reflection film composition (product name: ARC29,manufactured by Brewer Science Ltd.) was applied to a 12-inch siliconwafer using a spinner, and the composition was then baked and dried at205° C. for 60 seconds on a hotplate, thereby forming an organicanti-reflection film having a film thickness of 89 nm.

Then, the resist compositions was applied onto the anti-reflection filmusing a spinner, and was then prebaked (PAB) on a hotplate at atemperature indicated in Table 4 for 60 seconds and dried, therebyforming a resist film having a film thickness of 100 nm.

Subsequently, the resist film was selectively irradiated with an ArFexcimer laser (193 nm) through a photomask (6% halftone), using animmersion lithography ArF exposure apparatus NSR-5609B (manufactured byNikon Corporation; NA (numerical aperture)=1.07; Annular 0.97/0.78w/Polano; immersion medium: water). Further, PEB treatment was conductedat a temperature indicated in Table 4 for 60 seconds.

Next, a solvent development was conducted for 13 seconds at 23° C. usingmethyl amyl ketone (MAK) (2-heptanone), followed by drying by shaking.

As a result, in each of the examples, a contact hole pattern (CHpattern) in which holes having a diameter of 55 nm were equally spaced(pitch: 110 nm) was formed.

[Evaluation of EL]

The exposure dose with which a CH pattern was formed in theaforementioned [Formation of resist pattern 2] with holes having adimension of the target dimension ±5% (i.e., 53 nm to 58 nm) wasdetermined, and the EL (unit: %) was determined by the followingformula. The results are indicated “5% EL” in Table 4.EL (%)=(|E1−E2|/Eop)×100

In the formula, E1 represents the exposure dose (mJ/cm²) for forming aCH pattern with a hole diameter of 53 nm, E2 represents the exposuredose (mJ/cm²) for forming a CH pattern having a hole diameter of 58 nm,and Eop represents the optimum exposure dose with which the CH patternhaving a hole diameter of 55 nm was formed. Eop was determined by aconventional method.

[Evaluation of Circularity]

With respect to each CH pattern formed in the aforementioned [Formationof resist pattern 2], 25 holes in the CH pattern was observed from theupper side thereof using a measuring scanning electron microscope (SEM)(product name: S-9380, manufactured by Hitachi High-TechnologiesCorporation; acceleration voltage: 300V), and the distance from thecenter of the hole to the outer periphery thereof was measured in 24directions. From the results, the value of 3 times the standarddeviation σ (i.e., 3σ) was determined. The results are shown in Table 4.The smaller this 3σ value is, the higher the level of circularity of theholes.

[Evaluation of in-Plane Uniformity (CDU) of Pattern Size]

With respect to each CH pattern formed in the aforementioned [Formationof resist pattern 2], 100 holes in the CH pattern was observed from theupper side thereof using a measuring scanning electron microscope (SEM)(product name: S-9380, manufactured by Hitachi High-TechnologiesCorporation; acceleration voltage: 300V), and the hole diameter (nm) ofeach hole was measured.

From the results, the value of 3 times the standard deviation σ (i.e.,3σ) was determined. The results are indicated “CDU” in Table 4. Thesmaller the thus determined 3σ value is, the higher the level of thedimension uniformity (CD uniformity) of the plurality of holes formed inthe resist film.

[Measurement of Residual Film Ratio]

The film thickness of the CH pattern formed using each of resistcompositions in the aforementioned [Formation of resist pattern 2](i.e., film thickness of exposed portions after solvent development) wasdetermined, and the residual film ratio (unit: %) was determined by thefollowing formula. The results are shown in Table 4.residual film ratio (%)=(FT2/FT1)×100

In the aforementioned formula, FT1 shows the thickness (nm) of theresist film prior to exposure, and FT2 shows the film thickness (nm) ofCH patterns.

The film thickness was measured using Nanospec 6100A (manufactured byNanometrics Incorporated).

TABLE 4 Residual PAB/PEB 5% EL Circularity CDU film ratio (° C.) (%)(3σ) (3σ) (%) Comparative 100/85 3.5 3.20 10.50 58 Example 3 Comparative100/90 4.6 3.05 9.90 64 Example 4 Comparative 100/90 4.1 3.15 9.74 63Example 5 Comparative 100/90 4.5 3.45 10.73 64 Example 6 Example 5100/90 6.2 2.72 8.73 74 Example 6 100/90 5.8 2.69 8.68 77 Example 7100/90 5.2 2.81 8.55 75 Example 8 100/90 5.4 2.77 8.92 71 Example 9100/90 5.7 2.90 8.88 70 Comparative 120/85 4.7 3.01 10.07 63 Example 7Example 10 120/85 5.2 2.72 8.93 71

As shown in the aforementioned results, in the resist compositions ofExamples 5 to 9, lithography properties such as 5% EL, circularity andCDU were improved, as compared to Comparative Examples 3 to 6 which hadthe same composition except for the “structural unit containing alactone-containing cyclic group” contained in the component (A).Furthermore, the residual film ratio at exposed portions was high, andthe film shrinkage was suppressed.

Likewise, in the resist compositions of Example 10, lithographyproperties such as 5% EL, circularity and CDU were improved, as comparedto Comparative Example 7 which had the same composition except for the“structural unit containing a lactone-containing cyclic group” containedin the component (A). Furthermore, the residual film ratio at exposedportions was high, and the film shrinkage was suppressed.

Polymer Synthesis Example

Polymeric compounds 8 to 15 were produced in the same manner as inSynthesis Example 6 using the following monomers (1) to (9) which derivethe structural units constituting each polymeric compound. With respectto each of the obtained polymeric compounds, the copolymer compositionalratio (ratio (molar ratio) of the respective structural units within thestructural formula) as determined by carbon 13 nuclear magneticresonance spectroscopy (600 MHz-¹³C-NMR; internal standard:tetramethylsilane), and the weight average molecular weight (Mw) and thedispersity (Mw/Mn) determined by the polystyrene equivalent value asmeasured by GPC are shown in Tables 5 and 6.

TABLE 5 Polymeric compound 8 9 10 11 Monomer (1) 22.5 22.5 17.5 17.5 (2)22.5 22.5 17.5 (3) 17.5 (4) (5) 45 40 40 (6) 40 (7) (8) (9) Mw 5400 52003800 4500 Mw/Mn 1.69 1.66 1.69 1.66

TABLE 6 Polymeric compound 12 13 14 15 Monomer (1) 30 45 30 40 (2) 10(3) (4) 15 (5) 45 35 (6) (7) 40 40 (8) 10 10 20 10 (9) 10 10 Mw 48004900 3800 5900 Mw/Mn 1.69 1.66 1.69 1.66

The components were mixed with the obtained polymeric compound in themixing ratio indicated in following Table 7 to obtain resistcompositions (Examples 11 to 22, Comparative Examples 8 to 10).

TABLE 7 Compo- Compo- Compo- Compo- Component nent nent nent nent (S)(A) (B) (D) (F) (S)-4 (S)-5 (S)-6 Example 11 (A)-8  (B)-4 (D)-1 (F)-1(S)-4 (S)-5 (S)-6 [100] [14] [3]   [2] [1500] [900] [500] Example 12(A)-8  (B)-5 (D)-1 (F)-1 (S)-4 (S)-5 (S)-6 [100]  [1] [3]   [2] [1500][900] [500] Example 13 (A)-8  (B)-6 (D)-1 (F)-1 (S)-4 (S)-5 (S)-6 [100][20] [3]   [2] [1500] [900] [500] Example 14 (A)-8  (B)-7 (D)-1 (F)-1(S)-4 (S)-5 (S)-6 [100] [14] [3]   [2] [1500] [900] [500] Example 15(A)-8  (B)-8 (D)-1 (F)-1 (S)-4 (S)-5 (S)-6 [100] [13] [3]   [2] [1500][900] [500] Example 16 (A)-8  (B)-4 (D)-3 (F)-1 (S)-4 (S)-5 (S)-6 [100][14] [2.5] [2] [1500] [900] [500] Example 17 (A)-8  (B)-4 (D)-4 (F)-1(S)-4 (S)-5 (S)-6 [100] [14] [2.5] [2] [1500] [900] [500] Example 18(A)-8  (B)-4 (D)-1 (F)-3 (S)-4 (S)-5 (S)-6 [100] [14] [3]   [2] [1500][900] [500] Example 19 (A)-9  (B)-4 (D)-1 (F)-1 (S)-4 (S)-5 (S)-6 [100][14] [3]   [2] [1500] [900] [500] Example 20 (A)-10 (B)-4 (D)-1 (F)-1(S)-4 (S)-5 (S)-6 [100] [14] [3]   [2] 11500] [900] [500] Example 21(A)-11 (B)-4 (D)-1 (F)-1 (S)-4 (S)-5 (S)-6 [100] [14] [3]   [2] [1500][900] [500] Example 22 (A)-12 (B)-5 (D)-1 (F)-1 (S)-4 (S)-5 (S)-6 [100][13] [3]   [2] [1500] [900] [500] Comparative (A)-13 (B)-4 (D)-1 (F)-1(S)-4 (S)-5 (S)-6 Example 8 [100] [14] [3]   [2] [1500] [900] [500]Comparative (A)-14 (B)-4 (D)-1 (F)-1 (S)-4 (S)-5 (S)-6 Example 9 [100][14] [3]   [2] [1500] [900] [500] Comparative (A)-15 (B)-5 (D)-1 (F)-1(S)-4 (S)-5 (S)-6 Example 10 [100] [13] [3]   [2] [1500] [900] [500] InTable 7, the reference characters indicate the following. Further, thevalues in brackets [ ] indicate the amount (in terms of parts by weight)of the component added. (A)-8 to (A)-15: the aforementioned polymericcompounds 8 to 15, respectively (B)-4 to (B)-8: compounds (B)-4 to (B)-8shown below (D)-1: the aforementioned compound (D)-1 (D)-3 and (D)-4:compounds (D)-3 and (D)-4 shown below (F)-1: the aforementionedPolymer-F1 (F)-3: compound (F)-3 shown below (Mw: 20000, PDI: 1.44,molar ratio: l/m = 22/78) (S)-4: PGMEA (S)-5: PGME (S)-6: cyclohexanone[Chemical Formula 72]

Using the obtained resist compositions, the following evaluations wereconducted.

[Formation of Resist Pattern 3]

An organic anti-reflection film composition (product name: ARC95,manufactured by Brewer Science Ltd.) was applied to an 12-inch siliconwafer using a spinner, and the composition was then baked and dried on ahotplate at 205° C. for 60 seconds, thereby forming an organicanti-reflection film having a film thickness of 90 nm.

Then, each of the above resist composition indicated in Table 7(Examples 11 to 22, Comparative Examples 8 to 10) was applied to theorganic antireflection film using a coater/developer Lithius(manufactured by Tokyo Electron Ltd.), and was then prebaked (PAB) on ahotplate at 110° C. for 60 seconds and dried, thereby forming a resistfilm having a film thickness of 90 nm.

Subsequently, the resist film was selectively irradiated with an ArFexcimer laser (193 nm) through a transparent phase shift mask, using animmersion lithography ArF exposure apparatus NSR-S609B (manufactured byNikon Corporation; NA (numerical aperture)=1.07; Dipole(in/out=0.78/0.97) with Polano; immersion medium: water).

Further, PEB treatment was conducted at 95° C. for 60 seconds.

Next, by using a coater/developer Lithius (manufactured by TokyoElectron Ltd.), an alkali development was conducted for 10 seconds at23° C. in a 2.38% by weight aqueous solution of tetramethylammoniumhydroxide (TMAH) (product name: NMD-3; manufactured by Tokyo Ohka KogyoCo., Ltd.). Then, the resist was washed for 30 seconds with pure water,followed by drying by shaking.

As a result, in each of the examples, a 1:1 line and space pattern (LSpattern) having a line width of 50 nm and a pitch of 100 nm was formed.

With respect to the LS pattern formed in the above [Formation of resistpattern 3], 34:7 was determined as a yardstick for indicating LWR.

“3σ” indicates a value of 3 times the standard deviation (σ) (i.e.,3(s)) (unit: nm) determined by measuring the line width at 400 points inthe lengthwise direction of the line using a scanning electronmicroscope (product name: S-9220, manufactured by HitachiHigh-Technologies Corporation; acceleration voltage: 800V). The smallerthis 3s value is, the lower the level of roughness of the line sidewalls, indicating that a LS pattern with a uniform width was obtained.The results are indicated under “LWR (nm)” in Table 8.

[Measurement of Pattern Height]

The pattern height of the LS pattern formed in the aforementioned[Formation of resist pattern 3] was measured using a wafershape/characteristic measurement apparatus (product name: SCD-XT,manufactured by KLA-TENCOR Corporation). The results are shown in Table8.

TABLE 8 LWR (nm) Height (nm) Example 11 2.7 88 Example 12 2.7 87.5Example 13 2.8 86.7 Example 14 2.7 87.4 Example 15 2.9 89.1 Example 162.6 87.3 Example 17 2.5 87.5 Example 18 2.8 89.1 Example 19 3 86.5Example 20 2.6 88.2 Example 21 2.8 86.5 Example 22 3.4 85.6 Comparative2.9 84 Example 8 Comparative 3 83 Example 9 Comparative 3.7 79.2 Example10

As seen from the results, it was confirmed that the resist compositionsof Examples 11 to 22 exhibited the same or higher level of LWR andpattern height, as compared to the resist compositions of ComparativeExamples 8 to 10.

While preferred embodiments of the invention have been described andillustrated above, it should be understood that these are exemplary ofthe invention and are not to be considered as limiting. Additions,omissions, substitutions, and other modifications can be made withoutdeparting from the spirit or scope of the present invention.Accordingly, the invention is not to be considered as being limited bythe foregoing description, and is only limited by the scope of theappended claims.

What is claimed is:
 1. A resist composition which generates acid uponexposure and exhibits changed solubility in a developing solution by theaction of acid, comprising a base component (A) which exhibits changedsolubility in a developing solution by the action of acid, and an acidgenerator component (B) which generates acid upon exposure, wherein thebase component (A) comprises a polymeric compound (A1) having astructural unit (a0) represented by general formula (a0-1) shown below:

wherein R represents a hydrogen atom, or a methyl group; A″ representsan oxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbonatoms which may contain an oxygen atom or a sulfur atom; R¹ represents alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group; V¹⁰ represents an arylene group, analkylene group or a single bond; and L¹ represents —C(═O)—O—V¹—C(═O)—,—C(═O)—O—V²—O—V¹—C(═O)—, —C(═O)—O—V³—C(═O)—O—V¹—C(═O)—,—C(═O)—O—Ar—O—V¹—C(═O)—, —C(═O)—NH—V¹—C(═O)—, —C(═O)—NH—Ar—C(═O)—,—C(═O)—O—V⁴—NH—C(═O)—, S(═O)₂—, —C(═O)—O—V⁵—, —O—V⁵—, or —O—V¹—C(═O)—;wherein V¹ to V⁵ each independently represents a chain alkylene group,and Ar represents an arylene group, wherein the lactone-containingcyclic group is represented by any one of formulae (a2-r-2) to (a2-r-7)shown below, the —SO₂— containing cyclic group is represented by any oneof formulae (a5-r-1) to (a5-r-4) shown below, and thecarbonate-containing cyclic group is represented by any one of formulae(ax3-r-1) to (ax3-r-3) shown below:

wherein each Ra′²¹ independently represents a hydrogen atom, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group;R″ represents a hydrogen atom or an alkyl group; A″ represents an oxygenatom, a sulfur atom or an alkylene group of 1 to 5 carbon atoms whichmay contain an oxygen atom or a sulfur atom; and m′ represents 0 or 1;

wherein each Ra′⁵¹ independently represents a hydrogen atom, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group;R″ represents a hydrogen atom or an alkyl group; A″ represents an oxygenatom, a sulfur atom or an alkylene group of 1 to 5 carbon atoms whichmay contain an oxygen atom or a sulfur atom; and n′ represents aninteger of 0 to 2; and

wherein each Ra′^(x31) independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; p′ represents aninteger of 0 to 2; and q′ represents 0 or
 1. 2. The resist compositionaccording to claim 1, wherein the polymeric compound (A1) furthercomprises a structural unit (a1) containing an acid decomposable groupthat increases polarity by the action of acid.
 3. The resist compositionaccording to claim 1, wherein the structural unit (a0) is represented bygeneral formula (a0-11) or (a0-12) shown below:

wherein R represents a hydrogen atom or a methyl group, A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; R¹ represents alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group; represents —C(═O)—O—V¹—C(═O)—,—C(═O)—O—V²—O—V¹—C(═O)—, —C(═O)—O—V³—C(═O)—O—V¹—C(═O)—,—C(═O)—O—Ar—O—V¹—C(═O)—, —C(═O)—NH—V¹—C(═O)—, —C(═O)—NH—Ar—C(═O)—,—C(═O)—O—V⁴—NH—C(═O)—, —S(═O)₂— or —C(═O)—O—V⁵—; V¹² represents anarylene group; L¹² represents —C(═O)—NH—V¹—C(═O)—, —O—V¹—C(═O)— or—O—V⁵—; V¹ to V⁵ each independently represents a chain alkylene group;and Ar represents an arylene group, wherein the lactone-containingcyclic group is represented by any one of the formulae (a2-r-2) to(a2-r-7), the —SO₂— containing cyclic group is represented by any one ofthe formulae (a5-r-1) to (a5-r-4), and the carbonate-containing cyclicgroup is represented by any one of the formulae (ax3-r-1) to (ax3-r-3).4. A method of forming a resist pattern, comprising: forming a resistfilm on a substrate using a resist composition of claim 1; conductingexposure of the resist film; and developing the resist film to form aresist pattern.
 5. A polymeric compound comprising a structural unit(a0) represented by general formula (a0-1) shown below:

wherein R represents a hydrogen atom, or a methyl group; A″ representsan oxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbonatoms which may contain an oxygen atom or a sulfur atom; R¹ represents alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group; V¹⁰ represents an arylene group, analkylene group or a single bond; and L¹ represents —C(═O)—O—V¹—C(═O)—,—C(═O)—O—V²—O—V¹—C(═O)—, —C(═O)—O—V³—C(═O)—O—V¹—C(═O)—,—C(═O)—O—Ar—O—V¹—C(═O)—, —C(═O)—NH—V¹—C(═O)—, —C(═O)—NH—Ar—C(═O)—,—C(═O)—O—V⁴—NH—C(═O)—, S(═O)₂—, —C(═O)—O—V⁵—, —O—V⁵—, or —O—V¹—C(═O)—,wherein V¹ to V⁵ each independently represents a chain alkylene group,and Ar represents an arylene group, wherein the lactone-containingcyclic group is represented by any one of formulae (a2-r-2) to (a2-r-7)shown below, the —SO₂— containing cyclic group is represented by any oneof formulae (a5-r-1) to (a5-r-4) shown below, and thecarbonate-containing cyclic group is represented by any one of formulae(ax3-r-1) to (ax3-r-3) shown below:

wherein each Ra′²¹ independently represents a hydrogen atom, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group;R″ represents a hydrogen atom or an alkyl group; A″ represents an oxygenatom, a sulfur atom or an alkylene group of 1 to 5 carbon atoms whichmay contain an oxygen atom or a sulfur atom; and m′ represents 0 or 1;

wherein each Ra′⁵¹ independently represents a hydrogen atom, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group;R″ represents a hydrogen atom or an alkyl group; A″ represents an oxygenatom, a sulfur atom or an alkylene group of 1 to 5 carbon atoms whichmay contain an oxygen atom or a sulfur atom; and n′ represents aninteger of 0 to 2; and

wherein each Ra′^(x31) independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; p′ represents aninteger of 0 to 2; and q′ represents 0 or
 1. 6. The polymeric compoundaccording to claim 5, further comprising a structural unit (a1)containing an acid decomposable group that exhibits increased polarityby the action of acid.
 7. The polymeric compound according to claim 5,wherein the structural unit (a0) is represented by general formula(a0-11) or (a0-12) shown below:

wherein R represents a hydrogen atom or a methyl group, A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; R¹ represents alactone-containing cyclic group, an —SO₂— containing cyclic group or acarbonate-containing cyclic group; represents —C(═O)—O—V¹—C(═O)—,—C(═O)—O—V²—O—V¹—C(═O)—, —C(═O)—O—V³—C(═O)—O—V¹—C(═O)—,—C(═O)—O—Ar—O—V¹—C(═O)—, —C(═O)—NH—V¹—C(═O)—, —C(═O)—NH—Ar—C(═O)—,—C(═O)—O—V⁴—NH—C(═O)—, —S(═O)₂— or —C(═O)—O—V⁵—; V¹² represents anarylene group; L¹² represents —C(═O)—NH—V¹—C(═O)—, —O—V¹—C(═O)— or—O—V⁵—; V¹ to V⁵ each independently represents an alkylene group; and Arrepresents an arylene group, wherein the lactone-containing cyclic groupis represented by any one of the formulae (a2-r-2) to (a2-r-7), the—SO₂— containing cyclic group is represented by any one of the formulae(a5-r-1) to (a5-r-4), and the carbonate-containing cyclic group isrepresented by any one of the formulae (ax3-r-1) to (ax3-r-3).
 8. Acompound represented by general formula (I) shown below:

wherein A″ represents an oxygen atom, a sulfur atom or an alkylene groupof 1 to 5 carbon atoms which may contain an oxygen atom or a sulfuratom; R¹ represents a lactone-containing cyclic group, an —SO₂—containing cyclic group or a carbonate-containing cyclic group; and R²represents CH₂═C(R)—V¹⁰-L¹-, wherein R represents a hydrogen atom, or amethyl group; V¹⁰ represents an arylene group, an alkylene group or asingle bond; L¹ represents —C(═O)—O—V¹—C(═O)—, —C(═O)—O—V²—O—V¹—C(═O)—,—C(═O)—O—V³—C(═O)—O—V¹—C(═O)—, —C(═O)—O—Ar—O—V¹—C(═O)—,—C(═O)—NH—V¹—C(═O)—, —C(═O)—NH—Ar—C(═O)—, —C(═O)—O—V⁴—NH—C(═O)—,S(═O)₂—, —C(═O)—O—V⁵—, —O—V⁵—, or —O—V¹—C(═O)—; wherein V¹ to V⁵ eachindependently represents a chain alkylene group, and Ar represents anarylene group, the lactone-containing cyclic group is represented by anyone of formulae (a2-r-2) to (a2-r-7) shown below, the —SO₂— containingcyclic group is represented by any one of formulae (a5-r-1) to (a5-r-4)shown below, and the carbonate-containing cyclic group is represented byany one of formulae (ax3-r-1) to (ax3-r-3) shown below:

wherein each Ra′²¹ independently represents a hydrogen atom, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group;R″ represents a hydrogen atom or an alkyl group; A″ represents an oxygenatom, a sulfur atom or an alkylene group of 1 to 5 carbon atoms whichmay contain an oxygen atom or a sulfur atom; and m′ represents 0 or 1;

wherein each Ra′⁵¹ independently represents a hydrogen atom, an alkylgroup, an alkoxy group, a halogen atom, a halogenated alkyl group, ahydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyano group;R″ represents a hydrogen atom or an alkyl group; A″ represents an oxygenatom, a sulfur atom or an alkylene group of 1 to 5 carbon atoms whichmay contain an oxygen atom or a sulfur atom; and n′ represents aninteger of 0 to 2; and

wherein each Ra′^(x31) independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; p′ represents aninteger of 0 to 2; and q′ represents 0 or
 1. 9. The compound accordingto claim 8, which is represented by any one of formulae shown below:

wherein R represents a hydrogen atom, or a methyl group.
 10. A resistcomposition which generates acid upon exposure and exhibits changedsolubility in a developing solution by the action of acid, comprising abase component (A) which exhibits changed solubility in a developingsolution by the action of acid, and an acid generator component (B)which generates acid upon exposure, wherein the base component (A)comprises a polymeric compound (A1) having a structural unit (a0)represented by general formula (a0) shown below:

wherein A″ represents an oxygen atom, a sulfur atom or an alkylene groupof 1 to 5 carbon atoms which may contain an oxygen atom or a sulfuratom; R¹ represents a carbonate-containing cyclic group; and W²represents a group which is formed by polymerization reaction of a groupcontaining an acryloyl group or a methacryloyl group, wherein thecarbonate-containing cyclic group is represented by any one of formulae(ax3-r-1) to (ax3-r-3) shown below:

wherein each Ra′^(x31) independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; p′ represents aninteger of 0 to 2; and q′ represents 0 or
 1. 11. A polymeric compoundcomprising a structural unit (a0) represented by general formula (a0)shown below:

wherein A″ represents an oxygen atom, a sulfur atom or an alkylene groupof 1 to 5 carbon atoms which may contain an oxygen atom or a sulfuratom; R¹ represents a carbonate-containing cyclic group; and W²represents a group which is formed by polymerization reaction of a groupcontaining an acryloyl group or a methacryloyl group, wherein thecarbonate-containing cyclic group is represented by any one of formulae(ax3-r-1) to (ax3-r-3) shown below:

wherein each Ra′^(x31) independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; p′ represents aninteger of 0 to 2; and q′ represents 0 or
 1. 12. A compound representedby general formula (I) shown below:

wherein A″ represents an oxygen atom, a sulfur atom or an alkylene groupof 1 to 5 carbon atoms which may contain an oxygen atom or a sulfuratom; R¹ represents a carbonate-containing cyclic group; and R²represents a group containing an acryloyl group or a methacryloyl group,wherein the carbonate-containing cyclic group is represented by any oneof formulae (ax3-r-1) to (ax3-r-3) shown below:

wherein each Ra′^(x31) independently represents a hydrogen atom, analkyl group, an alkoxy group, a halogen atom, a halogenated alkyl group,a hydroxy group, —COOR″, —OC(═O)R″, a hydroxyalkyl group or a cyanogroup; R″ represents a hydrogen atom or an alkyl group; A″ represents anoxygen atom, a sulfur atom or an alkylene group of 1 to 5 carbon atomswhich may contain an oxygen atom or a sulfur atom; p′ represents aninteger of 0 to 2; and q′ represents 0 or 1.